feat: cached gas prices

Refactor and features (#17 )
* feat: features and refactor * fixed return types * update README Co-authored-by: Danil Kovtonyuk <danx.kov@gmail.com>
2022-08-18 23:17:00 +10:00 · 2022-07-11 16:57:38 +10:00 · 2022-05-23 20:26:11 +10:00 · 2022-04-13 21:30:55 +10:00 · 2022-03-18 05:19:29 +10:00 · 2021-11-16 03:46:43 +10:00
51 changed files with 4730 additions and 1835 deletions
--- a/.eslintrc
+++ b/.eslintrc
@@ -0,0 +1,38 @@
+{
+  "env": {
+    "node": true,
+    "browser": true,
+    "es6": true,
+    "mocha": true
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+  "plugins": ["prettier", "eslint-plugin-import", "eslint-plugin-node", "eslint-plugin-promise", "@typescript-eslint"],
+  "extends": ["prettier", "eslint:recommended", "plugin:@typescript-eslint/recommended", "plugin:prettier/recommended"],
+  "globals": {
+    "Atomics": "readonly",
+    "SharedArrayBuffer": "readonly"
+  },
+  "parserOptions": {
+    "parser": "@typescript-eslint/parser",
+    "project": "./tsconfig.json",
+    "sourceType": "module",
+    "target": "esnext",
+    "module": "commonjs"
+  },
+  "rules": {
+    "node/no-callback-literal": 0,
+    "prettier/prettier": ["error", { "printWidth": 130 }],
+    "jsx-quotes": ["error", "prefer-single"],
+    "@typescript-eslint/restrict-template-expressions": ["warn", { "allowNumber": true }],
+    "@typescript-eslint/explicit-function-return-type": 0,
+    "@typescript-eslint/array-type": 2,
+    "@typescript-eslint/camelcase": 0,
+    "@typescript-eslint/consistent-type-definitions": 0,
+    "@typescript-eslint/no-empty-function": 2,
+    "@typescript-eslint/no-empty-interface": 2,
+    "@typescript-eslint/no-explicit-any": 2,
+    "@typescript-eslint/no-extra-non-null-assertion": 2,
+    "@typescript-eslint/require-await": 2,
+    "@typescript-eslint/no-floating-promises": 0,
+    "@typescript-eslint/strict-boolean-expressions": 0
+  }
+}
--- a/.github/workflows/nodejs.yml
+++ b/.github/workflows/nodejs.yml
@@ -0,0 +1,60 @@
+name: Node.js CI
+
+on:
+  push:
+    branches: ['*']
+    tags: ['v[0-9]+.[0-9]+.[0-9]+']
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - uses: actions/setup-node@v1
+        with:
+          node-version: 16.15.1
+      - run: yarn install --frozen-lockfile
+      - run: yarn test
+      - run: yarn lint
+
+  publish:
+    runs-on: ubuntu-latest
+    needs: [build]
+    if: startsWith(github.ref, 'refs/tags')
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - run: yarn install
+      - name: NPM login
+        # NPM doesn't understand env vars and needs auth file lol
+        run: echo "//registry.npmjs.org/:_authToken=${NPM_TOKEN}" > ~/.npmrc
+        env:
+          NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+      - name: Set vars
+        id: vars
+        run: |
+          echo "::set-output name=version::$(echo ${GITHUB_REF#refs/tags/v})"
+          echo "::set-output name=repo_name::$(echo ${GITHUB_REPOSITORY#*/})"
+      - name: Check package.json version vs tag
+        run: |
+          [ ${{ steps.vars.outputs.version }} = $(grep '"version":' package.json | grep -o "[0-9.]*") ] || (echo "Git tag doesn't match version in package.json" && false)
+      - name: Publish to npm
+        run: npm publish
+      - name: Create GitHub Release Draft
+        uses: actions/create-release@v1
+        with:
+          tag_name: ${{ github.ref }}
+          release_name: Release ${{ steps.vars.outputs.version }}
+          draft: true
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Telegram Message Notify
+        uses: appleboy/telegram-action@0.0.7
+        with:
+          to: ${{ secrets.TELEGRAM_CHAT_ID }}
+          token: ${{ secrets.TELEGRAM_BOT_TOKEN }}
+          message: 🚀 Published [${{ steps.vars.outputs.repo_name }}](https://github.com/${{ github.repository }}) version [${{ steps.vars.outputs.version }}](https://www.npmjs.com/package/${{ steps.vars.outputs.repo_name }}/v/${{ steps.vars.outputs.version }}) to npm
+          debug: true
+          format: markdown
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,91 @@
-node_modules
+# Created by .ignore support plugin (hsz.mobi)
+### Node template
+# Logs
+/logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
 lib
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (https://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directories
+node_modules/
+jspm_packages/
+
+# TypeScript v1 declaration files
+typings/
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variables file
+.env
+
+# parcel-bundler cache (https://parceljs.org/)
+.cache
+
+# next.js build output
+.next
+
+# nuxt.js build output
+.nuxt
+
+# Nuxt generate
+dist
+
+# vuepress build output
+.vuepress/dist
+
+# Serverless directories
+.serverless
+
+# IDE / Editor
+.idea
+
+# Service worker
+sw.*
+
+# macOS
+.DS_Store
+
+# Vim swap files
+*.swp
--- a/.nvmrc
+++ b/.nvmrc
@@ -0,0 +1 @@
+16.15.1
--- a/.prettierignore
+++ b/.prettierignore
@@ -0,0 +1 @@
+lib
--- a/.prettierrc
+++ b/.prettierrc
@@ -0,0 +1,8 @@
+{
+  "semi": false,
+  "trailingComma": "all",
+  "singleQuote": true,
+  "jsxSingleQuote": true,
+  "printWidth": 130,
+  "tabWidth": 2
+}
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -1,24 +0,0 @@
-{
-    // Use IntelliSense to learn about possible attributes.
-    // Hover to view descriptions of existing attributes.
-    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
-    "version": "0.2.0",
-    "configurations": [
-        {
-            "type": "node",
-            "request": "launch",
-            "name": "Mocha Current File",
-            "program": "${workspaceFolder}/node_modules/mocha/bin/_mocha",
-            "args": [
-              "--no-timeouts",
-              "--colors",
-              "${file}",
-              "--require",
-              "ts-node/register"
-            ],
-            "console": "integratedTerminal",
-            "sourceMaps": true,
-            "internalConsoleOptions": "neverOpen"
-      }
-    ]
-}
--- a/21
+++ b/21
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 PepperSec
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
--- a/README.md
+++ b/README.md
@@ -1,48 +1,310 @@
-# Gas Price Oracle library for Ethereum dApps
+# Gas Price Oracle library for Ethereum dApps [![GitHub Workflow Status](https://img.shields.io/github/workflow/status/peppersec/gas-price-oracle/Node.js%20CI)](https://github.com/peppersec/gas-price-oracle/actions) [![npm](https://img.shields.io/npm/v/gas-price-oracle)](https://www.npmjs.com/package/gas-price-oracle)
+
+This is a library with a collection of onchain and offchain gas price oracle URLs
+
+## Supported networks
+
+### Ethereum Mainnet
+
+Current offchain list:
+
+- https://ethgasstation.info/json/ethgasAPI.json
+- https://etherchain.org/api/gasnow
+
+Current onchain list:
+
+- [chainlink](https://etherscan.io/address/0x169e633a2d1e6c10dd91238ba11c4a708dfef37c#readContract)
+
+### Binance Smart Chain
+
+Current offchain list:
+
+- https://ztake.org/
+
+### Gnosis Chain
+
+Current offchain list:
+
+- https://blockscout.com/xdai/mainnet/api/v1/gas-price-oracle
+
+### Polygon (Matic) Network
+
+Current offchain list:
+
+- https://gasstation-mainnet.matic.network/
+
+### Avalanche C Network
+
+Current offchain list:
+
+- https://gavax.blockscan.com/gasapi.ashx?apikey=key&method=gasoracle
+
+## Installation

-## Instalation
 `npm i gas-price-oracle`
+or
+`yarn add gas-price-oracle`

 ## Import
-```js
-const { GasPriceOracle } = require('gas-price-oracle');
-```
-## Usage
-### Basic
-```js
-const oracle = new GasPriceOracle();

-oracle.gasPrices().then((gas) => {
-    console.log(gas)
-});
+```js
+const { GasPriceOracle } = require('gas-price-oracle')
+or
+import { GasPriceOracle } from 'gas-price-oracle'
 ```

+## Usage
+
+### Configuration
+
+```typescript
+type GasPrice = Record<'instant' | 'fast' | 'standard' | 'low', number>
+
+type EstimatedGasPrice = {
+  maxFeePerGas: number
+  baseFee: number | undefined
+  maxPriorityFeePerGas: number
+}
+
+type FallbackGasPrices = {
+  gasPrices?: GasPrice
+  estimated?: EstimatedGasPrice
+}
+
+type GasOracleOptions = {
+  chainId?: number
+  timeout?: number
+  defaultRpc?: string
+  blocksCount?: number
+  percentile?: number
+  blockTime?: number // seconds
+  shouldCache?: boolean
+  fallbackGasPrices?: FallbackGasPrices
+}
+
+const options: GasOracleOptions = {
+  chainId: 1,
+  percentile: 5, // Which percentile of effective priority fees to include
+  blocksCount: 10, // How many blocks to consider for priority fee estimation
+  defaultRpc: 'https://api.mycryptoapi.com/eth',
+  blockTime: 10, // seconds
+  shouldCache: false,
+  timeout: 10000, // specifies the number of milliseconds before the request times out.
+  fallbackGasPrices: {
+    gasPrices: {
+      instant: 28,
+      fast: 22,
+      standard: 17,
+      low: 11,
+    },
+    estimated: {
+      maxFeePerGas: 20,
+      maxPriorityFeePerGas: 3,
+    },
+  },
+}
+```
+
+### The Oracle can cache rpc calls
+
+For caching needs to provide to GasOracleOptions
+
+`shouldCache: true`
+
+`blockTime: <Chain block time duration>`
+
+### EIP-1559 (estimated) gasPrice only
+
+```typescript
+const oracle = new GasPriceOracle({ chainId: 1 })
+
+type EstimatedGasPrice = {
+  maxFeePerGas: number
+  baseFee: number | undefined
+  maxPriorityFeePerGas: number
+}
+
+fallbackGasPrices: EstimatedGasPrice = {
+  maxFeePerGas: 20,
+  maxPriorityFeePerGas: 3,
+}
+
+oracle.eip1559.estimateFees(fallbackGasPrices).then((gasPrices: EstimatedGasPrice) => {
+  console.log(gasPrices) // { baseFee: 14, maxFeePerGas: 17, maxPriorityFeePerGas: 3 }
+})
+```
+
+### Legacy gasPrice only
+
+```typescript
+const oracle = new GasPriceOracle({ chainId: 1 })
+
+type GasPrice = Record<'instant' | 'fast' | 'standard' | 'low', number>
+
+fallbackGasPrices: GasPrice = {
+  instant: 28,
+  fast: 22,
+  standard: 17,
+  low: 11,
+}
+
+oracle.legacy.gasPrices(fallbackGasPrices).then((gasPrices: GasPrice) => {
+  console.log(gasPrices) // { instant: 21.5, fast: 19, standard: 17, low: 15 }
+})
+```
+
+The `oracle.legacy.gasPrices` method also accepts `shouldGetMedian` argument (`true`) by default. For more details see [below](#offchain-oracles-only-get-median-price).
+Under the hood it's a combination of `fetchMedianGasPriceOffChain`(`fetchGasPricesOffChain`) and `fetchGasPricesOnChain` methods.
+
+### Estimated gasPrices (EIP-1559) and Legacy gasPrice
+
+```ts
+const oracle = new GasPriceOracle(options)
+
+type GasPriceWithEstimate = {
+  gasPrices: GasPrice
+  estimate: EstimatedGasPrice
+}
+
+type GasPricesWithEstimateInput = {
+  shouldGetMedian?: boolean
+  fallbackGasPrices?: FallbackGasPrices
+}
+
+// optional fallbackGasPrices
+const fallbackGasPrices: FallbackGasPrices = {
+  gasPrices: {
+    instant: 28,
+    fast: 22,
+    standard: 17,
+    low: 11,
+  },
+  estimated: {
+    maxFeePerGas: 20,
+    maxPriorityFeePerGas: 3,
+  },
+}
+
+oracle.gasPricesWithEstimate({ fallbackGasPrices, shouldGetMedian: true }).then((gasPrices: GasPriceWithEstimate) => {
+  console.log(gasPrices) // {
+  // estimated: { baseFee: 14, maxFeePerGas: 17, maxPriorityFeePerGas: 3 },
+  // gasPrices: { instant: 21.5, fast: 19, standard: 17, low: 15 }
+  // }}
+})
+```
+
+### Estimated gasPrices (EIP-1559) or Legacy gasPrice
+
+```typescript
+const oracle = new GasPriceOracle(options)
+
+type GetGasPriceInput = {
+  isLegacy?: boolean
+  shouldGetMedian?: boolean
+  fallbackGasPrices?: GasPrice
+}
+
+// optional fallbackGasPrices
+const fallbackGasPrices: FallbackGasPrices = {
+  gasPrices: {
+    instant: 28,
+    fast: 22,
+    standard: 17,
+    low: 11,
+  },
+  estimated: {
+    maxFeePerGas: 20,
+    maxPriorityFeePerGas: 3,
+  },
+}
+
+oracle.gasPrices({ fallbackGasPrices, shouldGetMedian: true }).then((gasPrices: GasPrice | EstimatedGasPrice) => {
+  console.log(gasPrices) // {
+  // baseFee: 14, maxFeePerGas: 17, maxPriorityFeePerGas: 3 ||
+  // instant: 21.5, fast: 19, standard: 17, low: 15
+  // }}
+})
+```
+
+The `gasPrices` method also accepts `isLegacy` argument (`false`) by default. If `isLegacy: true` - `legacy gasPrice` will be provided. If the `estimate Gas` crashes, `legacy gas Price` will be provided.
+
+### Get transaction gasPrice params
+
+```typescript
+const oracle = new GasPriceOracle(options)
+
+type GetTxGasParamsInput = {
+  bumpPercent?: number
+  legacySpeed?: GasPriceKey
+  isLegacy?: boolean
+  shouldGetMedian?: boolean
+  fallbackGasPrices?: FallbackGasPrices
+}
+
+type GetTxGasParamsRes =
+  | {
+      gasPrice: number
+    }
+  | {
+      maxFeePerGas: number
+      maxPriorityFeePerGas: number
+    }
+
+const gasParams: GetTxGasParamsRes = await oracle.getTxGasParams({ legacySpeed: 'fast', bumpPercent: 30 })
+console.log(gasParams) // { maxFeePerGas: 17, maxPriorityFeePerGas: 3 } || { gasPrice: 19 }
+
+web3.eth.sendTransaction({
+  from: '0xEA674fdDe714fd979de3EdF0F56AA9716B898ec8',
+  to: '0xac03bb73b6a9e108530aff4df5077c2b3d481e5a',
+  nonce: '0',
+  gasLimit: '21000',
+  value: '10000000000',
+  ...gasParams,
+})
+```
+
+`bumpPercent` argument (`0` by default) - response data will increase by `bumpPercent`%.
+`legacySpeed` argument (`fast` by default) - select the speed of legacy gasPrice.
+
 ### Offchain oracles only
-```js
-const oracle = new GasPriceOracle();

-oracle.fetchGasPricesOffChain().then((gas) => {
-    console.log(gas)
-});
+```typescript
+const oracle = new GasPriceOracle({ chainId: 1 })
+
+// shouldGetMedian: boolean | undefined
+oracle.legacy.fetchGasPricesOffChain((shouldGetMedian = true)).then((gasPrices: GasPrice) => {
+  console.log(gasPrices) // { instant: 50, fast: 21, standard: 10, low: 3 }
+})
 ```

+### Offchain oracles only (get median price)
+
+```typescript
+const oracle = new GasPriceOracle({ chainId: 1 })
+
+oracle.legacy.fetchMedianGasPriceOffChain().then((gasPrices: GasPrice) => {
+  console.log(gasPrices) // { instant: 50, fast: 21, standard: 10, low: 3 }
+})
+```
+
+This command provides the median gas price of all configured oracles.
+
 ### Custom RPC URL for onchain oracles
-```js
-const customRpc = 'https://mainnet.infura.io/v3/<API_KEY>'
-const oracle = new GasPriceOracle(customRpc);

-oracle.fetchGasPricesOnChain().then((gas) => {
-    console.log(gas)
-});
+```typescript
+const defaultRpc = 'https://mainnet.infura.io/v3/<API_KEY>'
+const oracle = new GasPriceOracle({ defaultRpc, chainId: 1 })
+
+oracle.legacy.fetchGasPricesOnChain().then((gasPrices: number) => {
+  console.log(gasPrices) // 21
+})
 ```

-### Don't throw an error if oracles are down
-```js
-oracle.fetchGasPricesOnChain(false).then((gas) => {
-    console.log(gas)
-});
+To get gasPrices from a chain outside of the application's chain list (Binance, Gnosis, Polygon, Avalanche), you should enter the rpcUrl into initial GasPriceOracle options\_

-oracle.fetchGasPricesOffChain(false).then((gas) => {
-    console.log(gas)
-});
+```typescript
+const defaultRpc = 'https://rpc.goerli.mudit.blog/' // goerli public rpcUrl
+const oracle = new GasPriceOracle({ defaultRpc, chainId: 5 })
+
+oracle.gasPrices()
 ```
--- a/package-lock.json
+++ b/package-lock.json
--- a/package.json
+++ b/package.json
@@ -1,37 +1,64 @@
 {
  "name": "gas-price-oracle",
-  "version": "0.1.1",
+  "version": "0.5.1",
  "description": "Gas Price Oracle library for Ethereum dApps.",
-  "main": "lib/index.js",
-  "types": "lib/index.d.ts",
-  "prepare": "npm run build",
-  "prepublishOnly": "npm test && npm run lint",
+  "homepage": "https://github.com/peppersec/gas-price-oracle",
+  "main": "./lib/index.js",
+  "module": "./lib/esm/index.js",
+  "types": "./lib/index.d.ts",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/peppersec/gas-price-oracle.git"
+  },
  "scripts": {
-    "test": "mocha --timeout 30000 -r ts-node/register tests/*.test.ts",
-    "build": "tsc",
-    "lint": "tslint -p tsconfig.json"
+    "test": "ts-mocha --timeout 30000 --paths 'src/tests/*.test.ts'",
+    "build": "tsc && tsc-alias",
+    "build:esm": "tsc -p tsconfig.esm.json && tsc-alias -p tsconfig.esm.json",
+    "eslint": "eslint 'src/*.ts'",
+    "prettier:check": "prettier --check . --config .prettierrc",
+    "prettier:fix": "prettier --write . --config .prettierrc",
+    "lint": "yarn eslint && yarn prettier:check",
+    "prepare": "yarn build && yarn build:esm",
+    "prepublishOnly": "yarn test && yarn lint"
  },
  "author": "Alexey Pertsev <alexey@peppersec.com> (https://peppersec.com)",
-  "keywords": ["Gas", "Gas price", "Ethereum", "Oracle"],
+  "keywords": [
+    "Gas",
+    "Gas price",
+    "Ethereum",
+    "Oracle",
+    "EIP-1559",
+    "London Fork"
+  ],
  "license": "MIT",
  "devDependencies": {
    "@types/chai": "^4.2.11",
+    "@types/chai-as-promised": "^7.1.3",
    "@types/mocha": "^7.0.2",
    "@types/mockery": "^1.4.29",
+    "@types/node": "^14.0.5",
+    "@typescript-eslint/eslint-plugin": "^4.4.1",
+    "@typescript-eslint/parser": "^4.4.1",
    "chai": "^4.2.0",
    "chai-as-promised": "^7.1.1",
+    "eslint": "^7.11.0",
+    "eslint-config-prettier": "^6.13.0",
+    "eslint-plugin-import": "^2.26.0",
+    "eslint-plugin-node": "^11.1.0",
+    "eslint-plugin-prettier": "^3.1.4",
+    "eslint-plugin-promise": "^6.0.0",
    "mocha": "^7.2.0",
    "mockery": "^2.1.0",
-    "tslint": "^6.1.2",
-    "tslint-config-standard": "^9.0.0"
+    "prettier": "^2.1.2",
+    "ts-mocha": "^10.0.0",
+    "ts-node": "^8.10.1",
+    "tsc-alias": "^1.6.11",
+    "typescript": "^4.7.4"
  },
  "dependencies": {
-    "@types/node": "^14.0.5",
-    "@types/node-fetch": "^2.5.7",
+    "axios": "^0.21.2",
    "bignumber.js": "^9.0.0",
-    "node-fetch": "^2.6.0",
-    "ts-node": "^8.10.1",
-    "typescript": "^3.9.3"
+    "node-cache": "^5.1.2"
  },
  "files": [
    "lib/**/*"
--- a/src/config.ts
+++ b/src/config.ts
@@ -1,62 +0,0 @@
-
-import { OffChainOracle, OnChainOracle } from './types';
-
-const ethgasstation: OffChainOracle = {
-  name: 'ethgasstation',
-  url: 'https://ethgasstation.info/json/ethgasAPI.json',
-  instantPropertyName: 'fastest',
-  fastPropertyName: 'fast',
-  standardPropertyName: 'average',
-  lowPropertyName: 'safeLow',
-  denominator: 10
-};
-
-const zoltu: OffChainOracle = {
-  name: 'zoltu',
-  url: 'https://gas-oracle.zoltu.io/',
-  instantPropertyName: 'percentile_99',
-  fastPropertyName: 'percentile_90',
-  standardPropertyName: 'percentile_60',
-  lowPropertyName: 'percentile_30',
-  denominator: 1
-};
-
-const etherchain: OffChainOracle = {
-  name: 'etherchain',
-  url: 'https://www.etherchain.org/api/gasPriceOracle',
-  instantPropertyName: 'fastest',
-  fastPropertyName: 'fast',
-  standardPropertyName: 'standard',
-  lowPropertyName: 'safeLow',
-  denominator: 1
-};
-
-const poa: OffChainOracle = {
-  name: 'poa',
-  url: 'https://gasprice.poa.network/',
-  instantPropertyName: 'instant',
-  fastPropertyName: 'fast',
-  standardPropertyName: 'standard',
-  lowPropertyName: 'slow',
-  denominator: 1
-};
-
-const chainlink: OnChainOracle = {
-  name: 'chainlink',
-  callData: '0x50d25bcd',
-  contract: '0xA417221ef64b1549575C977764E651c9FAB50141',
-  denominator: '1000000000'
-};
-
-export const offChainOracles: { [key: string]: OffChainOracle } = {
-  ethgasstation, zoltu, poa, etherchain
-};
-
-export const onChainOracles: { [key: string]: OnChainOracle } = {
-  chainlink
-};
-
-export default {
-  offChainOracles,
-  onChainOracles
-};
--- a/src/config/arbitrum.ts
+++ b/src/config/arbitrum.ts
@@ -0,0 +1,10 @@
+import { OffChainOracles, OnChainOracles } from '@/services'
+
+export const offChainOracles: OffChainOracles = {}
+
+export const onChainOracles: OnChainOracles = {}
+
+export default {
+  offChainOracles,
+  onChainOracles,
+}
--- a/src/config/avax.ts
+++ b/src/config/avax.ts
@@ -0,0 +1,23 @@
+import { OffChainOracle, OffChainOracles, OnChainOracles } from '@/services'
+
+const avalancheGasStation: OffChainOracle = {
+  name: 'avalancheGasStation',
+  url: 'https://gavax.blockscan.com/gasapi.ashx?apikey=key&method=gasoracle',
+  instantPropertyName: 'FastGasPrice',
+  fastPropertyName: 'FastGasPrice',
+  standardPropertyName: 'ProposeGasPrice',
+  lowPropertyName: 'SafeGasPrice',
+  denominator: 1,
+  additionalDataProperty: 'result',
+}
+
+export const offChainOracles: OffChainOracles = {
+  avalancheGasStation,
+}
+
+export const onChainOracles: OnChainOracles = {}
+
+export default {
+  offChainOracles,
+  onChainOracles,
+}
--- a/src/config/bsc.ts
+++ b/src/config/bsc.ts
@@ -0,0 +1,23 @@
+import { OffChainOracle, OffChainOracles, OnChainOracles } from '@/services'
+
+const ztake: OffChainOracle = {
+  name: 'ztake',
+  url: 'https://blockchains.ztake.org/api/h6WnmwNqw9CAJHzej5W4gD6LZ9n7v8EK/gasprice/bsc/',
+  instantPropertyName: 'percentile_60',
+  fastPropertyName: 'percentile_50',
+  standardPropertyName: 'percentile_40',
+  lowPropertyName: 'percentile_30',
+  denominator: 1,
+  additionalDataProperty: null,
+}
+
+export const offChainOracles: OffChainOracles = {
+  ztake,
+}
+
+export const onChainOracles: OnChainOracles = {}
+
+export default {
+  offChainOracles,
+  onChainOracles,
+}
--- a/src/config/index.ts
+++ b/src/config/index.ts
@@ -0,0 +1,78 @@
+import bscOracles from './bsc'
+import xdaiOracles from './xdai'
+import avalancheOracles from './avax'
+import mainnetOracles from './mainnet'
+import polygonOracles from './polygon'
+import optimismOracles from './optimism'
+import arbitrumOracles from './arbitrum'
+
+import { NetworksConfig } from '@/types'
+
+export enum ChainId {
+  MAINNET = 1,
+  BSC = 56,
+  XDAI = 100,
+  POLYGON = 137,
+  OPTIMISM = 10,
+  ARBITRUM = 42161,
+  AVAX = 43114,
+}
+
+export const NETWORKS: Record<number, NetworksConfig> = {
+  [ChainId.MAINNET]: {
+    oracles: mainnetOracles,
+    rpcUrl: 'https://api.mycryptoapi.com/eth',
+    defaultGasPrice: 22,
+    maxGasPrice: 1500,
+    blocksCount: 10,
+    percentile: 5,
+  },
+  [ChainId.BSC]: {
+    oracles: bscOracles,
+    rpcUrl: 'https://bsc-dataseed1.ninicoin.io',
+    defaultGasPrice: 5,
+    maxGasPrice: 200,
+    blocksCount: 10,
+    percentile: 5,
+  },
+  [ChainId.XDAI]: {
+    oracles: xdaiOracles,
+    rpcUrl: 'https://rpc.gnosischain.com',
+    defaultGasPrice: 5,
+    maxGasPrice: 200,
+    blocksCount: 200,
+    percentile: 5,
+  },
+  [ChainId.POLYGON]: {
+    oracles: polygonOracles,
+    rpcUrl: 'https://rpc-mainnet.maticvigil.com',
+    defaultGasPrice: 75,
+    maxGasPrice: 1000,
+    blocksCount: 10,
+    percentile: 5,
+  },
+  [ChainId.OPTIMISM]: {
+    oracles: optimismOracles,
+    rpcUrl: 'https://mainnet.optimism.io',
+    defaultGasPrice: 0.001,
+    maxGasPrice: 5,
+    blocksCount: 10,
+    percentile: 5,
+  },
+  [ChainId.ARBITRUM]: {
+    oracles: arbitrumOracles,
+    rpcUrl: 'https://arb1.arbitrum.io/rpc',
+    defaultGasPrice: 3,
+    maxGasPrice: 15,
+    blocksCount: 10,
+    percentile: 5,
+  },
+  [ChainId.AVAX]: {
+    oracles: avalancheOracles,
+    rpcUrl: 'https://api.avax.network/ext/bc/C/rpc',
+    defaultGasPrice: 50,
+    maxGasPrice: 1000,
+    blocksCount: 10,
+    percentile: 5,
+  },
+}
--- a/src/config/mainnet.ts
+++ b/src/config/mainnet.ts
@@ -0,0 +1,44 @@
+import { OffChainOracle, OffChainOracles, OnChainOracle, OnChainOracles } from '@/services'
+
+const ethgasstation: OffChainOracle = {
+  name: 'ethgasstation',
+  url: 'https://ethgasstation.info/json/ethgasAPI.json',
+  instantPropertyName: 'fastest',
+  fastPropertyName: 'fast',
+  standardPropertyName: 'average',
+  lowPropertyName: 'safeLow',
+  denominator: 10,
+  additionalDataProperty: null,
+}
+
+const etherchain: OffChainOracle = {
+  name: 'etherchain',
+  url: 'https://etherchain.org/api/gasnow',
+  instantPropertyName: 'rapid',
+  fastPropertyName: 'fast',
+  standardPropertyName: 'standard',
+  lowPropertyName: 'slow',
+  denominator: 1e9,
+  additionalDataProperty: 'data',
+}
+
+const chainlink: OnChainOracle = {
+  name: 'chainlink',
+  callData: '0x50d25bcd',
+  contract: '0x169E633A2D1E6c10dD91238Ba11c4A708dfEF37C',
+  denominator: '1000000000',
+}
+
+export const offChainOracles: OffChainOracles = {
+  ethgasstation,
+  etherchain,
+}
+
+export const onChainOracles: OnChainOracles = {
+  chainlink,
+}
+
+export default {
+  offChainOracles,
+  onChainOracles,
+}
--- a/src/config/optimism.ts
+++ b/src/config/optimism.ts
@@ -0,0 +1,18 @@
+import { OffChainOracles, OnChainOracle, OnChainOracles } from '@/services'
+
+export const offChainOracles: OffChainOracles = {}
+
+const optimism: OnChainOracle = {
+  name: 'optimism',
+  callData: '0xfe173b97',
+  denominator: '1000000000',
+  contract: '0x420000000000000000000000000000000000000F',
+}
+export const onChainOracles: OnChainOracles = {
+  optimism,
+}
+
+export default {
+  offChainOracles,
+  onChainOracles,
+}
--- a/src/config/polygon.ts
+++ b/src/config/polygon.ts
@@ -0,0 +1,23 @@
+import { OffChainOracle, OffChainOracles, OnChainOracles } from '@/services'
+
+const maticGasStation: OffChainOracle = {
+  name: 'maticGasStation',
+  url: 'https://gasstation-mainnet.matic.network',
+  instantPropertyName: 'fastest',
+  fastPropertyName: 'fast',
+  standardPropertyName: 'standard',
+  lowPropertyName: 'safeLow',
+  denominator: 1,
+  additionalDataProperty: null,
+}
+
+export const offChainOracles: OffChainOracles = {
+  maticGasStation,
+}
+
+export const onChainOracles: OnChainOracles = {}
+
+export default {
+  offChainOracles,
+  onChainOracles,
+}
--- a/src/config/xdai.ts
+++ b/src/config/xdai.ts
@@ -0,0 +1,23 @@
+import { OffChainOracle, OffChainOracles, OnChainOracles } from '@/services'
+
+const blockscout: OffChainOracle = {
+  name: 'blockscout',
+  url: 'https://blockscout.com/xdai/mainnet/api/v1/gas-price-oracle',
+  instantPropertyName: 'fast',
+  fastPropertyName: 'average',
+  standardPropertyName: 'slow',
+  lowPropertyName: 'slow',
+  denominator: 1,
+  additionalDataProperty: null,
+}
+
+export const offChainOracles: OffChainOracles = {
+  blockscout,
+}
+
+export const onChainOracles: OnChainOracles = {}
+
+export default {
+  offChainOracles,
+  onChainOracles,
+}
--- a/src/constants/index.ts
+++ b/src/constants/index.ts
@@ -0,0 +1,27 @@
+import BigNumber from 'bignumber.js'
+
+const GWEI = 1e9
+const DEFAULT_TIMEOUT = 10000
+
+const ROUND_UP = 1
+const ROUND_DOWN = 2
+const GWEI_PRECISION = 9
+const INT_PRECISION = 0
+
+const SUCCESS_STATUS = 200
+const BG_ZERO = new BigNumber(0)
+const PERCENT_MULTIPLIER = 100
+const DEFAULT_BLOCK_DURATION = 10
+
+export {
+  GWEI,
+  DEFAULT_TIMEOUT,
+  ROUND_UP,
+  ROUND_DOWN,
+  GWEI_PRECISION,
+  INT_PRECISION,
+  SUCCESS_STATUS,
+  BG_ZERO,
+  PERCENT_MULTIPLIER,
+  DEFAULT_BLOCK_DURATION,
+}
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,134 +1 @@
-import fetch from 'node-fetch';
-import config from './config';
-import { GasPrice, OffChainOracle, OnChainOracle } from './types';
-import BigNumber from 'bignumber.js';
-
-export class GasPriceOracle {
-  lastGasPrice: GasPrice = {
-    instant: 40,
-    fast: 21,
-    standard: 10,
-    low: 1
-  };
-  defaultRpc = 'https://api.mycryptoapi.com/eth';
-  offChainOracles = { ...config.offChainOracles };
-  onChainOracles = { ...config.onChainOracles };
-
-  constructor(defaultRpc?: string) {
-    if (defaultRpc) {
-      this.defaultRpc = defaultRpc;
-    }
-  }
-
-  async fetchGasPricesOffChain(throwIfFailsToFetch = true): Promise<GasPrice> {
-    for (let oracle of Object.values(this.offChainOracles)) {
-      const { name, url, instantPropertyName, fastPropertyName, standardPropertyName, lowPropertyName, denominator } = oracle;
-      try {
-        const response = await fetch(url);
-        if (response.status === 200) {
-          const gas = await response.json();
-          if (Number(gas[fastPropertyName]) === 0) {
-            throw new Error(`${name} oracle provides corrupted values`);
-          }
-          const gasPrices: GasPrice = {
-            instant: parseFloat(gas[instantPropertyName]) / denominator,
-            fast: parseFloat(gas[fastPropertyName]) / denominator,
-            standard: parseFloat(gas[standardPropertyName]) / denominator,
-            low: parseFloat(gas[lowPropertyName]) / denominator
-          };
-          this.lastGasPrice = gasPrices;
-          return this.lastGasPrice;
-        } else {
-          throw new Error(`Fetch gasPrice from ${name} oracle failed. Trying another one...`);
-        }
-      } catch (e) {
-        console.error(e.message);
-      }
-    }
-    if (throwIfFailsToFetch) {
-      throw new Error('All oracles are down. Probaly network error.');
-    }
-    return this.lastGasPrice;
-  }
-
-  async fetchGasPricesOnChain(throwIfFailsToFetch = true): Promise<GasPrice> {
-    for (let oracle of Object.values(this.onChainOracles)) {
-      const { name, callData, contract, denominator } = oracle;
-      let { rpc } = oracle;
-      rpc = rpc ? rpc : this.defaultRpc;
-      const body = { jsonrpc: '2.0',
-        id: 1337,
-        method: 'eth_call',
-        params: [{ 'data': callData, 'to': contract }, 'latest']
-      };
-      try {
-        const response = await fetch(rpc, {
-          headers: {
-            'content-type': 'application/json'
-          },
-          body: JSON.stringify(body),
-          method: 'POST'
-        });
-        if (response.status === 200) {
-          const { result } = await response.json();
-          let fastGasPrice = new BigNumber(result);
-          if (fastGasPrice.isZero()) {
-            throw new Error(`${name} oracle provides corrupted values`);
-          }
-          fastGasPrice = fastGasPrice.div(denominator);
-          const gasPrices: GasPrice = {
-            instant: fastGasPrice.multipliedBy(1.3).toNumber(),
-            fast: fastGasPrice.toNumber(),
-            standard: fastGasPrice.multipliedBy(0.85).toNumber(),
-            low: fastGasPrice.multipliedBy(0.5).toNumber()
-          };
-          this.lastGasPrice = gasPrices;
-          return this.lastGasPrice;
-        } else {
-          throw new Error(`Fetch gasPrice from ${name} oracle failed. Trying another one...`);
-        }
-      } catch (e) {
-        console.error(e.message);
-      }
-    }
-    if (throwIfFailsToFetch) {
-      throw new Error('All oracles are down. Probaly network error.');
-    }
-    return this.lastGasPrice;
-  }
-
-  async gasPrices(): Promise<GasPrice> {
-    let gas = this.lastGasPrice;
-    try {
-      gas = await this.fetchGasPricesOffChain();
-      return gas;
-    } catch (e) {
-      console.log('Failed to fetch gas prices from offchain oracles. Trying onchain ones...');
-    }
-
-    try {
-      gas = await this.fetchGasPricesOnChain();
-      return gas;
-    } catch (e) {
-      console.log('Failed to fetch gas prices from onchain oracles. Last known gas will be returned');
-    }
-
-    return gas;
-  }
-
-  addOffChainOracle(oracle: OffChainOracle) {
-    this.offChainOracles[oracle.name] = oracle;
-  }
-
-  addOnChainOracle(oracle: OnChainOracle) {
-    this.onChainOracles[oracle.name] = oracle;
-  }
-
-  removeOnChainOracle(name: string) {
-    delete this.onChainOracles[name];
-  }
-
-  removeOffChainOracle(name: string) {
-    delete this.offChainOracles[name];
-  }
-}
+export * from '@/services/gas-price-oracle'
--- a/src/services/cacher/cacheNode.ts
+++ b/src/services/cacher/cacheNode.ts
@@ -0,0 +1,20 @@
+import NodeCache, { Options } from 'node-cache'
+
+export class NodeJSCache<T> {
+  private nodeCache: NodeCache
+  constructor(params: Options) {
+    this.nodeCache = new NodeCache(params)
+  }
+
+  async get(key: string): Promise<T | undefined> {
+    return await this.nodeCache.get<T>(key)
+  }
+
+  async set(key: string, value: T): Promise<boolean> {
+    return await this.nodeCache.set(key, value)
+  }
+
+  async has(key: string): Promise<boolean> {
+    return await this.nodeCache.has(key)
+  }
+}
--- a/src/services/cacher/index.ts
+++ b/src/services/cacher/index.ts
@@ -0,0 +1 @@
+export * from './cacheNode'
--- a/src/services/gas-estimation/constants.ts
+++ b/src/services/gas-estimation/constants.ts
@@ -0,0 +1,26 @@
+// How many blocks to consider for priority fee estimation
+import BigNumber from 'bignumber.js'
+import { EstimatedGasPrice } from './types'
+
+const FEE_HISTORY_BLOCKS = 10
+// Which percentile of effective priority fees to include
+const FEE_HISTORY_PERCENTILE = 5
+
+const DEFAULT_BASE_FEE = 20
+const DEFAULT_PRIORITY_FEE = 3
+const PRIORITY_FEE_INCREASE_BOUNDARY = 200 // %
+
+const FALLBACK_ESTIMATE: EstimatedGasPrice = {
+  baseFee: DEFAULT_BASE_FEE,
+  maxPriorityFeePerGas: DEFAULT_PRIORITY_FEE,
+  maxFeePerGas: new BigNumber(DEFAULT_PRIORITY_FEE).plus(DEFAULT_BASE_FEE).toNumber(),
+}
+
+export {
+  DEFAULT_BASE_FEE,
+  FALLBACK_ESTIMATE,
+  FEE_HISTORY_BLOCKS,
+  DEFAULT_PRIORITY_FEE,
+  FEE_HISTORY_PERCENTILE,
+  PRIORITY_FEE_INCREASE_BOUNDARY,
+}
--- a/src/services/gas-estimation/eip1559.ts
+++ b/src/services/gas-estimation/eip1559.ts
@@ -0,0 +1,156 @@
+import BigNumber from 'bignumber.js'
+
+import { FeeHistory, Block } from '@/types'
+import { Config, EstimateOracle, EstimatedGasPrice, CalculateFeesParams, GasEstimationOptionsPayload } from './types'
+
+import { ChainId, NETWORKS } from '@/config'
+import { RpcFetcher, NodeJSCache } from '@/services'
+import { findMax, fromNumberToHex, fromWeiToGwei, getMedian } from '@/utils'
+import { BG_ZERO, DEFAULT_BLOCK_DURATION, PERCENT_MULTIPLIER } from '@/constants'
+
+import { DEFAULT_PRIORITY_FEE, PRIORITY_FEE_INCREASE_BOUNDARY, FEE_HISTORY_BLOCKS, FEE_HISTORY_PERCENTILE } from './constants'
+
+// !!! MAKE SENSE ALL CALCULATIONS IN GWEI !!!
+export class Eip1559GasPriceOracle implements EstimateOracle {
+  public configuration: Config = {
+    shouldCache: false,
+    chainId: ChainId.MAINNET,
+    fallbackGasPrices: undefined,
+    blockTime: DEFAULT_BLOCK_DURATION,
+    blocksCount: NETWORKS[ChainId.MAINNET].blocksCount,
+    percentile: NETWORKS[ChainId.MAINNET].percentile,
+  }
+  private fetcher: RpcFetcher
+
+  private cache: NodeJSCache<EstimatedGasPrice>
+  private FEES_KEY = (chainId: ChainId) => `estimate-fee-${chainId}`
+
+  constructor({ fetcher, ...options }: GasEstimationOptionsPayload) {
+    this.fetcher = fetcher
+    const chainId = options?.chainId || this.configuration.chainId
+    this.configuration.blocksCount = NETWORKS[chainId]?.blocksCount || FEE_HISTORY_BLOCKS
+    this.configuration.percentile = NETWORKS[chainId]?.percentile || FEE_HISTORY_PERCENTILE
+
+    if (options) {
+      this.configuration = { ...this.configuration, ...options }
+    }
+
+    this.cache = new NodeJSCache({ stdTTL: this.configuration.blockTime, useClones: false })
+  }
+
+  public async estimateFees(fallbackGasPrices?: EstimatedGasPrice): Promise<EstimatedGasPrice> {
+    try {
+      const cacheKey = this.FEES_KEY(this.configuration.chainId)
+      const cachedFees = await this.cache.get(cacheKey)
+
+      if (cachedFees) {
+        return cachedFees
+      }
+
+      const { data: latestBlock } = await this.fetcher.makeRpcCall<{ result: Block }>({
+        method: 'eth_getBlockByNumber',
+        params: ['latest', false],
+      })
+
+      if (!latestBlock.result.baseFeePerGas) {
+        throw new Error('An error occurred while fetching current base fee, falling back')
+      }
+
+      const baseFee = fromWeiToGwei(latestBlock.result.baseFeePerGas)
+
+      const blockCount = fromNumberToHex(this.configuration.blocksCount)
+      const rewardPercentiles: number[] = [this.configuration.percentile]
+
+      const { data } = await this.fetcher.makeRpcCall<{ result: FeeHistory }>({
+        method: 'eth_feeHistory',
+        params: [blockCount, 'latest', rewardPercentiles],
+      })
+
+      const fees = await this.calculateFees({ baseFee, feeHistory: data.result })
+      if (this.configuration.shouldCache) {
+        await this.cache.set(cacheKey, fees)
+      }
+
+      return fees
+    } catch (err) {
+      if (fallbackGasPrices) {
+        return fallbackGasPrices
+      }
+      if (this.configuration.fallbackGasPrices) {
+        return this.configuration.fallbackGasPrices
+      }
+      throw err
+    }
+  }
+
+  private calculatePriorityFeeEstimate(feeHistory?: FeeHistory) {
+    if (!feeHistory) {
+      return null
+    }
+
+    const rewards = feeHistory.reward
+      ?.map((r) => fromWeiToGwei(r[0]))
+      .filter((r) => r.isGreaterThan(0))
+      .sort()
+
+    if (!rewards) {
+      return null
+    }
+
+    // Calculate percentage increases from between ordered list of fees
+    const percentageIncreases = rewards.reduce<BigNumber[]>((acc, curr, i, arr) => {
+      if (i !== arr.length - 1) {
+        const next = arr[i + 1]
+        const percentageIncrease = next.minus(curr).dividedBy(curr).multipliedBy(PERCENT_MULTIPLIER)
+        acc.push(percentageIncrease)
+      }
+
+      return acc
+    }, [])
+
+    const { highest, index } = findMax(percentageIncreases)
+    // If we have big increased in value, we could be considering "outliers" in our estimate
+    // Skip the low elements and take a new median
+    const values =
+      highest.isGreaterThanOrEqualTo(PRIORITY_FEE_INCREASE_BOUNDARY) && index >= getMedian(rewards)
+        ? rewards.slice(index)
+        : rewards
+
+    return values[getMedian(values)]
+  }
+
+  private async getPriorityFromChain(feeHistory?: FeeHistory) {
+    try {
+      const { data } = await this.fetcher.makeRpcCall<{ result: string }>({
+        method: 'eth_maxPriorityFeePerGas',
+        params: [],
+      })
+
+      return fromWeiToGwei(data.result)
+    } catch (err) {
+      return this.calculatePriorityFeeEstimate(feeHistory)
+    }
+  }
+
+  private async calculateFees({ baseFee, feeHistory }: CalculateFeesParams): Promise<EstimatedGasPrice> {
+    const estimatedPriorityFee = await this.getPriorityFromChain(feeHistory)
+
+    const { highest: maxPriorityFeePerGas } = findMax([estimatedPriorityFee ?? BG_ZERO, new BigNumber(DEFAULT_PRIORITY_FEE)])
+
+    const maxFeePerGas = baseFee.plus(maxPriorityFeePerGas)
+
+    if (this.checkIsGreaterThanMax(maxFeePerGas) || this.checkIsGreaterThanMax(maxPriorityFeePerGas)) {
+      throw new Error('Estimated gas fee was much higher than expected, erroring')
+    }
+
+    return {
+      baseFee: baseFee.toNumber(),
+      maxFeePerGas: maxFeePerGas.toNumber(),
+      maxPriorityFeePerGas: maxPriorityFeePerGas.toNumber(),
+    }
+  }
+
+  private checkIsGreaterThanMax(value: BigNumber): boolean {
+    return value.isGreaterThanOrEqualTo(NETWORKS[this.configuration.chainId]?.maxGasPrice) || false
+  }
+}
--- a/src/services/gas-estimation/index.ts
+++ b/src/services/gas-estimation/index.ts
@@ -0,0 +1,2 @@
+export * from './eip1559'
+export * from './types'
--- a/src/services/gas-estimation/types.ts
+++ b/src/services/gas-estimation/types.ts
@@ -0,0 +1,39 @@
+import BigNumber from 'bignumber.js'
+
+import { FeeHistory } from '@/types'
+import { RpcFetcher } from '@/services'
+
+export type EstimatedGasPrice = {
+  maxFeePerGas: number
+  baseFee: number | undefined
+  maxPriorityFeePerGas: number
+}
+
+export type EstimateFeesParams = {
+  blocksCount: number
+  percentile: number
+}
+
+export type CalculateFeesParams = {
+  baseFee: BigNumber
+  feeHistory?: FeeHistory
+}
+
+export type Options = {
+  chainId?: number
+  blocksCount?: number
+  percentile?: number
+  blockTime?: number
+  shouldCache?: boolean
+  fallbackGasPrices: EstimatedGasPrice | undefined
+}
+
+export type GasEstimationOptionsPayload = Options & {
+  fetcher: RpcFetcher
+}
+
+export type Config = Required<Options> & { fallbackGasPrices?: EstimatedGasPrice }
+export abstract class EstimateOracle {
+  public configuration: Config
+  public abstract estimateFees(fallbackGasPrices?: EstimatedGasPrice): Promise<EstimatedGasPrice>
+}
--- a/src/services/gas-price-oracle/gas-price-oracle.ts
+++ b/src/services/gas-price-oracle/gas-price-oracle.ts
@@ -0,0 +1,96 @@
+import {
+  GasOracleOptions,
+  GasPricesWithEstimateInput,
+  GasPriceWithEstimate,
+  GetGasPriceInput,
+  GetTxGasParamsInput,
+  GetTxGasParamsRes,
+  OracleProvider,
+} from './types'
+
+import { ChainId, NETWORKS } from '@/config'
+import { DEFAULT_TIMEOUT } from '@/constants'
+import { bumpOnPercent, fromGweiToWeiHex } from '@/utils'
+
+import {
+  RpcFetcher,
+  GasPrice,
+  LegacyOracle,
+  EstimateOracle,
+  EstimatedGasPrice,
+  LegacyGasPriceOracle,
+  Eip1559GasPriceOracle,
+} from '@/services'
+
+export class GasPriceOracle implements OracleProvider {
+  public eip1559: EstimateOracle
+  public legacy: LegacyOracle
+  public fetcher: RpcFetcher
+  private chainId: ChainId
+  public constructor(options?: GasOracleOptions) {
+    const timeout = options?.timeout ?? DEFAULT_TIMEOUT
+    this.chainId = options?.chainId || ChainId.MAINNET
+    const defaultRpc = options?.defaultRpc || NETWORKS[this.chainId].rpcUrl
+
+    this.fetcher = new RpcFetcher(defaultRpc, timeout)
+
+    const { gasPrices, estimated } = options?.fallbackGasPrices || {}
+
+    const payload = { ...options, fetcher: this.fetcher }
+    this.legacy = new LegacyGasPriceOracle({
+      ...payload,
+      fallbackGasPrices: gasPrices,
+    })
+
+    this.eip1559 = new Eip1559GasPriceOracle({
+      ...payload,
+      fallbackGasPrices: estimated,
+    })
+  }
+
+  public async gasPrices(payload: GetGasPriceInput = {}): Promise<GasPrice | EstimatedGasPrice> {
+    const { fallbackGasPrices, shouldGetMedian, isLegacy = false } = payload
+    if (isLegacy) {
+      return await this.legacy.gasPrices(fallbackGasPrices?.gasPrices, shouldGetMedian)
+    }
+    try {
+      return await this.eip1559.estimateFees(fallbackGasPrices?.estimated)
+    } catch {
+      return await this.legacy.gasPrices(fallbackGasPrices?.gasPrices, shouldGetMedian)
+    }
+  }
+
+  public async getTxGasParams(payload: GetTxGasParamsInput = {}): Promise<GetTxGasParamsRes> {
+    const { fallbackGasPrices, shouldGetMedian, isLegacy = false, bumpPercent = 0, legacySpeed = 'fast' } = payload
+
+    if (isLegacy) {
+      const legacyGasPrice = await this.legacy.gasPrices(fallbackGasPrices?.gasPrices, shouldGetMedian)
+
+      return { gasPrice: fromGweiToWeiHex(bumpOnPercent(legacyGasPrice[legacySpeed], bumpPercent)) }
+    }
+
+    try {
+      const eipParams = await this.eip1559.estimateFees(fallbackGasPrices?.estimated)
+      return {
+        maxFeePerGas: fromGweiToWeiHex(bumpOnPercent(eipParams.maxFeePerGas, bumpPercent)),
+        maxPriorityFeePerGas: fromGweiToWeiHex(bumpOnPercent(eipParams.maxPriorityFeePerGas, bumpPercent)),
+      }
+    } catch {
+      const legacyGasPrice = await this.legacy.gasPrices(fallbackGasPrices?.gasPrices, shouldGetMedian)
+
+      return { gasPrice: fromGweiToWeiHex(bumpOnPercent(legacyGasPrice[legacySpeed], bumpPercent)) }
+    }
+  }
+
+  public async gasPricesWithEstimate(payload: GasPricesWithEstimateInput = {}): Promise<GasPriceWithEstimate> {
+    const { fallbackGasPrices, shouldGetMedian } = payload
+
+    const estimate = await this.eip1559.estimateFees(fallbackGasPrices?.estimated)
+    const gasPrices = await this.legacy.gasPrices(fallbackGasPrices?.gasPrices, shouldGetMedian)
+
+    return {
+      estimate,
+      gasPrices,
+    }
+  }
+}
--- a/src/services/gas-price-oracle/index.ts
+++ b/src/services/gas-price-oracle/index.ts
@@ -0,0 +1,2 @@
+export * from './gas-price-oracle'
+export * from './types'
--- a/src/services/gas-price-oracle/types.ts
+++ b/src/services/gas-price-oracle/types.ts
@@ -0,0 +1,56 @@
+import { RpcFetcher, GasPrice, LegacyOracle, EstimatedGasPrice, EstimateOracle, GasPriceKey } from '@/services'
+
+export type GetTxGasParamsInput = GetGasPriceInput & {
+  bumpPercent?: number
+  legacySpeed?: GasPriceKey
+}
+
+export type GetTxGasParamsRes =
+  | {
+      gasPrice: string
+    }
+  | {
+      maxFeePerGas: string
+      maxPriorityFeePerGas: string
+    }
+
+export type GetGasPriceInput = {
+  isLegacy?: boolean
+  shouldGetMedian?: boolean
+  fallbackGasPrices?: FallbackGasPrices
+}
+
+export type FallbackGasPrices = {
+  gasPrices?: GasPrice
+  estimated?: EstimatedGasPrice
+}
+
+export type GasPricesWithEstimateInput = {
+  shouldGetMedian?: boolean
+  fallbackGasPrices?: FallbackGasPrices
+}
+
+export type GasOracleOptions = {
+  chainId?: number
+  timeout?: number
+  defaultRpc?: string
+  blocksCount?: number
+  percentile?: number
+  blockTime?: number
+  shouldCache?: boolean
+  fallbackGasPrices?: FallbackGasPrices
+}
+
+export type GasPriceWithEstimate = {
+  gasPrices: GasPrice
+  estimate: EstimatedGasPrice
+}
+
+export interface OracleProvider {
+  eip1559: EstimateOracle
+  legacy: LegacyOracle
+  fetcher: RpcFetcher
+  gasPrices: (payload: GetGasPriceInput) => Promise<GasPrice | EstimatedGasPrice>
+  gasPricesWithEstimate: (payload: GasPricesWithEstimateInput) => Promise<GasPriceWithEstimate>
+  getTxGasParams: (payload: GetTxGasParamsInput) => Promise<GetTxGasParamsRes>
+}
--- a/src/services/index.ts
+++ b/src/services/index.ts
@@ -0,0 +1,7 @@
+export * from './gas-price-oracle'
+
+export * from './gas-estimation'
+export * from './legacy-gas-price'
+
+export * from './cacher'
+export * from './rpcFetcher'
--- a/src/services/legacy-gas-price/constants.ts
+++ b/src/services/legacy-gas-price/constants.ts
@@ -0,0 +1,10 @@
+const DEFAULT_GAS_PRICE = { instant: 0, fast: 0, standard: 0, low: 0 }
+
+const MULTIPLIERS = {
+  instant: 1.3,
+  standard: 0.85,
+  low: 0.5,
+  fast: 1,
+}
+
+export { MULTIPLIERS, DEFAULT_GAS_PRICE }
--- a/src/services/legacy-gas-price/index.ts
+++ b/src/services/legacy-gas-price/index.ts
@@ -0,0 +1,2 @@
+export * from './legacy'
+export * from './types'
--- a/src/services/legacy-gas-price/legacy.ts
+++ b/src/services/legacy-gas-price/legacy.ts
@@ -0,0 +1,317 @@
+import axios from 'axios'
+import BigNumber from 'bignumber.js'
+
+import {
+  GasPrice,
+  GasPriceKey,
+  LegacyOracle,
+  OnChainOracle,
+  OffChainOracle,
+  LegacyOptions,
+  OnChainOracles,
+  OffChainOracles,
+  LegacyOptionsPayload,
+  GetGasPriceFromRespInput,
+} from './types'
+
+import { ChainId, NETWORKS } from '@/config'
+import { RpcFetcher, NodeJSCache } from '@/services'
+import { GWEI, DEFAULT_TIMEOUT, GWEI_PRECISION, DEFAULT_BLOCK_DURATION } from '@/constants'
+
+import { MULTIPLIERS, DEFAULT_GAS_PRICE } from './constants'
+
+export class LegacyGasPriceOracle implements LegacyOracle {
+  static getMedianGasPrice(gasPrices: GasPrice[]): GasPrice {
+    const medianGasPrice: GasPrice = DEFAULT_GAS_PRICE
+
+    const results: Record<GasPriceKey, number[]> = {
+      instant: [],
+      fast: [],
+      standard: [],
+      low: [],
+    }
+
+    for (const gasPrice of gasPrices) {
+      results.instant.push(gasPrice.instant)
+      results.fast.push(gasPrice.fast)
+      results.standard.push(gasPrice.standard)
+      results.low.push(gasPrice.low)
+    }
+
+    for (const type of Object.keys(medianGasPrice) as (keyof GasPrice)[]) {
+      const allPrices = results[type].sort((a, b) => a - b)
+      if (allPrices.length === 1) {
+        medianGasPrice[type] = allPrices[0]
+        continue
+      } else if (allPrices.length === 0) {
+        continue
+      }
+      const isEven = allPrices.length % 2 === 0
+      const middle = Math.floor(allPrices.length / 2)
+      medianGasPrice[type] = isEven ? (allPrices[middle - 1] + allPrices[middle]) / 2.0 : allPrices[middle]
+    }
+
+    return LegacyGasPriceOracle.normalize(medianGasPrice)
+  }
+
+  static getMultipliedPrices(gasPrice: number): GasPrice {
+    return {
+      instant: gasPrice * MULTIPLIERS.instant,
+      fast: gasPrice * MULTIPLIERS.fast,
+      standard: gasPrice * MULTIPLIERS.standard,
+      low: gasPrice * MULTIPLIERS.low,
+    }
+  }
+
+  static normalize(_gas: GasPrice): GasPrice {
+    const format = {
+      groupSeparator: '',
+      decimalSeparator: '.',
+    }
+
+    const gas: GasPrice = { ..._gas }
+    for (const type of Object.keys(gas) as (keyof GasPrice)[]) {
+      gas[type] = Number(new BigNumber(gas[type]).toFormat(GWEI_PRECISION, format))
+    }
+
+    return gas
+  }
+
+  static getCategorize(gasPrice: number): GasPrice {
+    return LegacyGasPriceOracle.normalize(LegacyGasPriceOracle.getMultipliedPrices(gasPrice))
+  }
+
+  static getGasPriceFromResponse(payload: GetGasPriceFromRespInput): number {
+    const { response, fetcherName, denominator = GWEI } = payload
+    let fastGasPrice = new BigNumber(response)
+    if (fastGasPrice.isZero()) {
+      throw new Error(`${fetcherName} provides corrupted values`)
+    }
+    fastGasPrice = fastGasPrice.div(denominator)
+    return fastGasPrice.toNumber()
+  }
+
+  public lastGasPrice: GasPrice
+  public onChainOracles: OnChainOracles = {}
+  public offChainOracles: OffChainOracles = {}
+  public configuration: Required<LegacyOptions> = {
+    shouldCache: false,
+    chainId: ChainId.MAINNET,
+    timeout: DEFAULT_TIMEOUT,
+    blockTime: DEFAULT_BLOCK_DURATION,
+    defaultRpc: NETWORKS[ChainId.MAINNET].rpcUrl,
+    fallbackGasPrices: LegacyGasPriceOracle.getMultipliedPrices(NETWORKS[ChainId.MAINNET].defaultGasPrice),
+  }
+
+  private readonly fetcher: RpcFetcher
+
+  private cache: NodeJSCache<GasPrice>
+  private LEGACY_KEY = (chainId: ChainId) => `legacy-fee-${chainId}`
+
+  constructor({ fetcher, ...options }: LegacyOptionsPayload) {
+    this.fetcher = fetcher
+    if (options) {
+      this.configuration = { ...this.configuration, ...options }
+    }
+
+    const { defaultGasPrice } = NETWORKS[ChainId.MAINNET]
+    const fallbackGasPrices = this.configuration.fallbackGasPrices || LegacyGasPriceOracle.getMultipliedPrices(defaultGasPrice)
+    this.configuration.fallbackGasPrices = LegacyGasPriceOracle.normalize(fallbackGasPrices)
+
+    const network = NETWORKS[this.configuration.chainId]?.oracles
+    if (network) {
+      this.offChainOracles = { ...network.offChainOracles }
+      this.onChainOracles = { ...network.onChainOracles }
+    }
+
+    this.cache = new NodeJSCache({ stdTTL: this.configuration.blockTime, useClones: false })
+  }
+
+  public addOffChainOracle(oracle: OffChainOracle): void {
+    this.offChainOracles[oracle.name] = oracle
+  }
+
+  public addOnChainOracle(oracle: OnChainOracle): void {
+    this.onChainOracles[oracle.name] = oracle
+  }
+
+  public removeOnChainOracle(name: string): void {
+    delete this.onChainOracles[name]
+  }
+
+  public removeOffChainOracle(name: string): void {
+    delete this.offChainOracles[name]
+  }
+
+  public async fetchGasPricesOnChain(): Promise<number> {
+    for (const oracle of Object.values(this.onChainOracles)) {
+      const { name, callData, contract, denominator, rpc } = oracle
+
+      try {
+        const response = await this.fetcher.makeRpcCall<{ result: string | number }>({
+          rpc,
+          method: 'eth_call',
+          params: [{ data: callData, to: contract }, 'latest'],
+        })
+
+        if (response.status === 200) {
+          return LegacyGasPriceOracle.getGasPriceFromResponse({
+            denominator,
+            fetcherName: `${name} oracle`,
+            response: response.data.result,
+          })
+        }
+        throw new Error(`Fetch gasPrice from ${name} oracle failed. Trying another one...`)
+      } catch (e) {
+        console.error(e.message)
+      }
+    }
+    throw new Error('All oracles are down. Probably a network error.')
+  }
+
+  public async fetchGasPriceFromRpc(): Promise<number> {
+    try {
+      const { status, data } = await this.fetcher.makeRpcCall<{ result: string | number }>({
+        params: [],
+        method: 'eth_gasPrice',
+      })
+
+      if (status === 200) {
+        return LegacyGasPriceOracle.getGasPriceFromResponse({
+          fetcherName: 'Default RPC',
+          response: data.result,
+        })
+      }
+
+      throw new Error(`Fetch gasPrice from default RPC failed..`)
+    } catch (e) {
+      console.error(e.message)
+      throw new Error('Default RPC is down. Probably a network error.')
+    }
+  }
+
+  public async fetchGasPricesOffChain(shouldGetMedian = true): Promise<GasPrice> {
+    if (shouldGetMedian) {
+      return await this.fetchMedianGasPriceOffChain()
+    }
+
+    for (const oracle of Object.values(this.offChainOracles)) {
+      try {
+        return await this.askOracle(oracle)
+      } catch (e) {
+        console.info(`${oracle} has error - `, e.message)
+        continue
+      }
+    }
+    throw new Error('All oracles are down. Probably a network error.')
+  }
+
+  public async fetchMedianGasPriceOffChain(): Promise<GasPrice> {
+    const promises: Promise<GasPrice>[] = []
+
+    for (const oracle of Object.values(this.offChainOracles) as OffChainOracle[]) {
+      promises.push(this.askOracle(oracle))
+    }
+
+    const settledPromises = await Promise.allSettled(promises)
+
+    const allGasPrices = settledPromises.reduce((acc: GasPrice[], result) => {
+      if (result.status === 'fulfilled') {
+        acc.push(result.value)
+        return acc
+      }
+      return acc
+    }, [])
+
+    if (allGasPrices.length === 0) {
+      throw new Error('All oracles are down. Probably a network error.')
+    }
+
+    return LegacyGasPriceOracle.getMedianGasPrice(allGasPrices)
+  }
+
+  public async gasPrices(fallbackGasPrices?: GasPrice, shouldGetMedian = true): Promise<GasPrice> {
+    if (!this.lastGasPrice) {
+      this.lastGasPrice = fallbackGasPrices || this.configuration.fallbackGasPrices
+    }
+
+    const cacheKey = this.LEGACY_KEY(this.configuration.chainId)
+    const cachedFees = await this.cache.get(cacheKey)
+
+    if (cachedFees) {
+      return cachedFees
+    }
+
+    if (Object.keys(this.offChainOracles).length > 0) {
+      try {
+        this.lastGasPrice = await this.fetchGasPricesOffChain(shouldGetMedian)
+        if (this.configuration.shouldCache) {
+          await this.cache.set(cacheKey, this.lastGasPrice)
+        }
+        return this.lastGasPrice
+      } catch (e) {
+        console.error('Failed to fetch gas prices from offchain oracles...')
+      }
+    }
+
+    if (Object.keys(this.onChainOracles).length > 0) {
+      try {
+        const fastGas = await this.fetchGasPricesOnChain()
+
+        this.lastGasPrice = LegacyGasPriceOracle.getCategorize(fastGas)
+        if (this.configuration.shouldCache) {
+          await this.cache.set(cacheKey, this.lastGasPrice)
+        }
+        return this.lastGasPrice
+      } catch (e) {
+        console.error('Failed to fetch gas prices from onchain oracles...')
+      }
+    }
+
+    try {
+      const fastGas = await this.fetchGasPriceFromRpc()
+
+      this.lastGasPrice = LegacyGasPriceOracle.getCategorize(fastGas)
+      if (this.configuration.shouldCache) {
+        await this.cache.set(cacheKey, this.lastGasPrice)
+      }
+      return this.lastGasPrice
+    } catch (e) {
+      console.error('Failed to fetch gas prices from default RPC. Last known gas will be returned')
+    }
+    return LegacyGasPriceOracle.normalize(this.lastGasPrice)
+  }
+
+  public async askOracle(oracle: OffChainOracle): Promise<GasPrice> {
+    const {
+      url,
+      name,
+      denominator,
+      lowPropertyName,
+      fastPropertyName,
+      instantPropertyName,
+      standardPropertyName,
+      additionalDataProperty,
+    } = oracle
+
+    const response = await axios.get(url, { timeout: this.configuration.timeout })
+
+    if (response.status === 200) {
+      const gas = additionalDataProperty ? response.data[additionalDataProperty] : response.data
+
+      if (Number(gas[fastPropertyName]) === 0) {
+        throw new Error(`${name} oracle provides corrupted values`)
+      }
+
+      const gasPrices: GasPrice = {
+        instant: parseFloat(gas[instantPropertyName]) / denominator,
+        fast: parseFloat(gas[fastPropertyName]) / denominator,
+        standard: parseFloat(gas[standardPropertyName]) / denominator,
+        low: parseFloat(gas[lowPropertyName]) / denominator,
+      }
+      return LegacyGasPriceOracle.normalize(gasPrices)
+    } else {
+      throw new Error(`Fetch gasPrice from ${name} oracle failed. Trying another one...`)
+    }
+  }
+}
--- a/src/services/legacy-gas-price/types.ts
+++ b/src/services/legacy-gas-price/types.ts
@@ -0,0 +1,80 @@
+import { RpcFetcher } from '@/services'
+
+export type OffChainOracle = {
+  url: string
+  name: string
+  denominator: number
+  lowPropertyName: string
+  fastPropertyName: string
+  instantPropertyName: string
+  standardPropertyName: string
+  additionalDataProperty: string | null
+}
+
+export type OffChainOracles = Record<string, OffChainOracle>
+
+export type OnChainOracle = {
+  name: string
+  rpc?: string
+  contract: string
+  callData: string
+  denominator: string
+}
+
+export type OnChainOracles = Record<string, OnChainOracle>
+
+export type AllOracles = {
+  onChainOracles: OnChainOracles
+  offChainOracles: OffChainOracles
+}
+
+export type NetworkConfig = Record<number, AllOracles>
+
+export type GasPriceKey = 'instant' | 'fast' | 'standard' | 'low'
+export type GasPrice = Record<GasPriceKey, number>
+
+export type LegacyOptions = {
+  chainId?: number
+  timeout?: number
+  blockTime?: number
+  defaultRpc?: string
+  shouldCache?: boolean
+  fallbackGasPrices?: GasPrice
+}
+
+export type LegacyOptionsPayload = LegacyOptions & {
+  fetcher: RpcFetcher
+}
+
+export type GetGasPriceFromRespInput = {
+  fetcherName: string
+  response: string | number
+  denominator?: number | string
+}
+
+type Config = Required<LegacyOptions>
+
+export abstract class LegacyOracle {
+  static normalize: (_gas: GasPrice) => GasPrice
+  static getCategorize: (gasPrice: number) => GasPrice
+  static getMultipliedPrices: (gasPrice: number) => GasPrice
+  static getMedianGasPrice: (gasPrices: GasPrice[]) => GasPrice
+  static getGasPriceFromResponse: (payload: GetGasPriceFromRespInput) => Promise<number>
+
+  public configuration: Config
+  public lastGasPrice: GasPrice
+  public onChainOracles: OnChainOracles
+  public offChainOracles: OffChainOracles
+
+  public abstract removeOnChainOracle(name: string): void
+  public abstract removeOffChainOracle(name: string): void
+  public abstract addOnChainOracle(oracle: OnChainOracle): void
+  public abstract addOffChainOracle(oracle: OffChainOracle): void
+
+  public fetchGasPriceFromRpc: () => Promise<number>
+  public fetchGasPricesOnChain: () => Promise<number>
+  public fetchMedianGasPriceOffChain: () => Promise<GasPrice>
+  public askOracle: (oracle: OffChainOracle) => Promise<GasPrice>
+  public fetchGasPricesOffChain: (shouldGetMedian?: boolean) => Promise<GasPrice>
+  public gasPrices: (fallbackGasPrices?: GasPrice, shouldGetMedian?: boolean) => Promise<GasPrice>
+}
--- a/src/services/rpcFetcher/fetcher.ts
+++ b/src/services/rpcFetcher/fetcher.ts
@@ -0,0 +1,23 @@
+import axios, { AxiosResponse } from 'axios'
+import { MakeRpcCallInput } from './types'
+
+export class RpcFetcher {
+  private readonly rpc: string
+  private readonly timeout: number
+
+  constructor(rpc: string, timeout: number) {
+    this.rpc = rpc
+    this.timeout = timeout
+  }
+
+  public async makeRpcCall<R>({ rpc, timeout, method, params }: MakeRpcCallInput): Promise<AxiosResponse<R>> {
+    const body = {
+      method,
+      id: 1337,
+      jsonrpc: '2.0',
+      params: params,
+    }
+
+    return await axios.post<R>(rpc || this.rpc, body, { timeout: timeout || this.timeout })
+  }
+}
--- a/src/services/rpcFetcher/index.ts
+++ b/src/services/rpcFetcher/index.ts
@@ -0,0 +1,2 @@
+export * from './fetcher'
+export * from './types'
--- a/src/services/rpcFetcher/types.ts
+++ b/src/services/rpcFetcher/types.ts
@@ -0,0 +1,7 @@
+export type Params = (string | number | number[] | Record<string, string | number | boolean> | boolean)[]
+export type MakeRpcCallInput = {
+  rpc?: string
+  method: string
+  timeout?: number
+  params: Params
+}
--- a/src/tests/complex.test.ts
+++ b/src/tests/complex.test.ts
@@ -0,0 +1,134 @@
+/* eslint-disable @typescript-eslint/no-var-requires */
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-ignore
+import chai from 'chai'
+import BigNumber from 'bignumber.js'
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-ignore
+import mockery from 'mockery'
+import { before, describe } from 'mocha'
+
+import { GWEI_PRECISION } from '@/constants'
+import { GasPriceOracle, GasPrice } from '@/services'
+
+chai.use(require('chai-as-promised'))
+chai.should()
+
+let oracle = new GasPriceOracle()
+
+before('before', async () => {
+  const gasPrice = await oracle.legacy.gasPrices()
+  console.log('legacy gasPrice - ', { gasPrice })
+})
+
+before('before', function () {
+  const axiosMock = {
+    get: () => {
+      throw new Error('axios GET method is mocked for tests')
+    },
+    post: () => {
+      throw new Error('axios POST method is mocked for tests')
+    },
+  }
+  mockery.registerMock('axios', axiosMock)
+})
+
+beforeEach('beforeEach', function () {
+  oracle = new GasPriceOracle()
+})
+
+const INJECTED_CHAIN_ID = 5
+const INJECTED_RPC_URL = 'https://rpc.goerli.mudit.blog/'
+
+describe('complex test', function () {
+  describe('fetching data', function () {
+    describe('should work with unexpected chainId', function () {
+      // it('legacy', async function () {
+      //   const newOracle = new GasPriceOracle({ chainId: ChainId.XDAI })
+      //
+      //   for (let i = 0; i < 100; i++) {
+      //     const res = await newOracle.eip1559.estimateFees()
+      //     await new Promise((r) =>
+      //       setTimeout(() => {
+      //         r(console.log(`res - ${i}`, res))
+      //       }, 3000),
+      //     )
+      //   }
+      // })
+
+      it('legacy', async function () {
+        const newOracle = new GasPriceOracle({ timeout: 1337, chainId: INJECTED_CHAIN_ID, defaultRpc: INJECTED_RPC_URL })
+
+        const goerliGas = (await newOracle.gasPrices({ isLegacy: true })) as unknown as GasPrice
+        if ('instant' in goerliGas) {
+          goerliGas.instant.should.be.a('number')
+          goerliGas.fast.should.be.a('number')
+          goerliGas.standard.should.be.a('number')
+          goerliGas.low.should.be.a('number')
+        }
+
+        newOracle.legacy.configuration.defaultRpc.should.be.equal(INJECTED_RPC_URL)
+        newOracle.legacy.configuration.chainId.should.be.equal(INJECTED_CHAIN_ID)
+      })
+      it('eip-1559', async function () {
+        const newOracle = new GasPriceOracle({ timeout: 1337, chainId: INJECTED_CHAIN_ID, defaultRpc: INJECTED_RPC_URL })
+
+        const goerliEstimated = await newOracle.eip1559.estimateFees()
+        if (goerliEstimated.baseFee) {
+          goerliEstimated.baseFee.should.be.a('number')
+
+          goerliEstimated.maxFeePerGas.should.be.at.least(goerliEstimated.baseFee)
+          const estimatedMaxFee = new BigNumber(goerliEstimated.baseFee)
+            .plus(goerliEstimated.maxPriorityFeePerGas)
+            .decimalPlaces(GWEI_PRECISION)
+            .toNumber()
+          goerliEstimated.maxFeePerGas.should.be.at.equal(estimatedMaxFee)
+        }
+
+        goerliEstimated.maxFeePerGas.should.be.a('number')
+        goerliEstimated.maxPriorityFeePerGas.should.be.a('number')
+
+        newOracle.legacy.configuration.defaultRpc.should.be.equal(INJECTED_RPC_URL)
+        newOracle.legacy.configuration.chainId.should.be.equal(INJECTED_CHAIN_ID)
+      })
+      it('without selected strategy', async function () {
+        const newOracle = new GasPriceOracle({ timeout: 1337, chainId: INJECTED_CHAIN_ID, defaultRpc: INJECTED_RPC_URL })
+
+        const gasPrice = await newOracle.gasPrices({})
+
+        if ('baseFee' in gasPrice && gasPrice.baseFee) {
+          gasPrice.baseFee.should.be.a('number')
+
+          gasPrice.maxFeePerGas.should.be.at.least(gasPrice.baseFee)
+          const estimatedMaxFee = new BigNumber(gasPrice.baseFee)
+            .plus(gasPrice.maxPriorityFeePerGas)
+            .decimalPlaces(GWEI_PRECISION)
+            .toNumber()
+          gasPrice.maxFeePerGas.should.be.at.equal(estimatedMaxFee)
+        }
+
+        if ('maxFeePerGas' in gasPrice) {
+          gasPrice.maxFeePerGas.should.be.a('number')
+          gasPrice.maxPriorityFeePerGas.should.be.a('number')
+        }
+
+        if ('instant' in gasPrice) {
+          gasPrice.instant.should.be.a('number')
+          gasPrice.fast.should.be.a('number')
+          gasPrice.standard.should.be.a('number')
+          gasPrice.low.should.be.a('number')
+        }
+
+        newOracle.legacy.configuration.defaultRpc.should.be.equal(INJECTED_RPC_URL)
+        newOracle.legacy.configuration.chainId.should.be.equal(INJECTED_CHAIN_ID)
+      })
+    })
+  })
+})
+
+after('after', function () {
+  after(function () {
+    mockery.disable()
+    mockery.deregisterMock('node-fetch')
+  })
+})
--- a/src/tests/eip1559.test.ts
+++ b/src/tests/eip1559.test.ts
@@ -0,0 +1,153 @@
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-ignore
+import chai from 'chai'
+import BigNumber from 'bignumber.js'
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-ignore
+import chaiAsPromised from 'chai-as-promised'
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-ignore
+import mockery from 'mockery'
+import { before, describe } from 'mocha'
+
+import { sleep } from '@/utils'
+import { ChainId, NETWORKS } from '@/config'
+import { GWEI_PRECISION } from '@/constants'
+
+import { GasPriceOracle } from '@/services/gas-price-oracle'
+import { EstimatedGasPrice } from '@/services/gas-estimation'
+import { FALLBACK_ESTIMATE } from '@/services/gas-estimation/constants'
+
+chai.use(chaiAsPromised)
+chai.should()
+
+let oracle = new GasPriceOracle()
+
+before('before', async () => {
+  const gasPrice = await oracle.eip1559.estimateFees()
+  console.log('eip estimation -', { gasPrice })
+})
+
+//
+beforeEach('beforeEach', function () {
+  oracle = new GasPriceOracle()
+})
+
+const INJECTED_RPC_URL = 'https://ethereum-rpc.trustwalletapp.com'
+describe('eip-1559 gasOracle', function () {
+  describe('eip constructor', function () {
+    it('should set default values', function () {
+      oracle.eip1559.configuration.blocksCount.should.be.equal(NETWORKS[oracle.eip1559.configuration.chainId].blocksCount)
+      oracle.eip1559.configuration.percentile.should.be.equal(NETWORKS[oracle.eip1559.configuration.chainId].percentile)
+    })
+
+    it('should set passed values', function () {
+      const newHistoryBlocks = 15
+      const newHistoryPercentile = 10
+
+      const newOracle = new GasPriceOracle({
+        blocksCount: newHistoryBlocks,
+        percentile: newHistoryPercentile,
+      })
+
+      newOracle.eip1559.configuration.blocksCount.should.be.equal(newHistoryBlocks)
+      newOracle.eip1559.configuration.percentile.should.be.equal(newHistoryPercentile)
+    })
+  })
+
+  const chains = Object.keys(NETWORKS).map((id) => Number(id))
+
+  chains.forEach((chainId) => {
+    let eipOracle = new GasPriceOracle({ chainId })
+
+    describe(`estimateGas ${chainId}`, function () {
+      it('should return error if not eip-1559 not supported', async function () {
+        if (chainId === ChainId.OPTIMISM || chainId === ChainId.ARBITRUM || chainId === ChainId.BSC) {
+          await eipOracle.eip1559
+            .estimateFees()
+            .should.be.rejectedWith('An error occurred while fetching current base fee, falling back')
+        }
+      })
+
+      if (chainId === ChainId.OPTIMISM || chainId === ChainId.ARBITRUM || chainId === ChainId.BSC) {
+        return
+      }
+
+      it('should work', async function () {
+        const estimateGas: EstimatedGasPrice = await eipOracle.eip1559.estimateFees()
+
+        console.log(`estimateGas ${chainId}`, estimateGas)
+        if (estimateGas.baseFee) {
+          estimateGas.baseFee.should.be.a('number')
+          estimateGas.maxFeePerGas.should.be.a('number')
+          estimateGas.maxPriorityFeePerGas.should.be.a('number')
+
+          estimateGas.maxFeePerGas.should.be.at.least(estimateGas.baseFee)
+          const estimatedMaxFee = new BigNumber(estimateGas.baseFee)
+            .plus(estimateGas.maxPriorityFeePerGas)
+            .decimalPlaces(GWEI_PRECISION)
+            .toNumber()
+          estimateGas.maxFeePerGas.should.be.at.equal(estimatedMaxFee)
+        }
+      })
+
+      it('should work with crashed rpc (return default data)', async function () {
+        eipOracle = new GasPriceOracle({ defaultRpc: 'wrongRpcUrl', chainId })
+        const estimateGas: EstimatedGasPrice = await eipOracle.eip1559.estimateFees(FALLBACK_ESTIMATE)
+
+        if (estimateGas.baseFee) {
+          estimateGas.baseFee.should.be.a('number')
+          estimateGas.maxFeePerGas.should.be.a('number')
+          estimateGas.maxPriorityFeePerGas.should.be.a('number')
+
+          estimateGas.baseFee.should.be.at.equal(FALLBACK_ESTIMATE.baseFee)
+          estimateGas.maxFeePerGas.should.be.at.equal(FALLBACK_ESTIMATE.maxFeePerGas)
+          estimateGas.maxPriorityFeePerGas.should.be.at.equal(FALLBACK_ESTIMATE.maxPriorityFeePerGas)
+        }
+      })
+
+      it('should work with custom rpc', async function () {
+        eipOracle = new GasPriceOracle({ defaultRpc: INJECTED_RPC_URL, chainId })
+        const estimateGas: EstimatedGasPrice = await eipOracle.eip1559.estimateFees(FALLBACK_ESTIMATE)
+
+        if (estimateGas.baseFee) {
+          estimateGas.baseFee.should.be.a('number')
+          estimateGas.maxFeePerGas.should.be.a('number')
+          estimateGas.maxPriorityFeePerGas.should.be.a('number')
+
+          const estimatedMaxFee = new BigNumber(estimateGas.baseFee)
+            .plus(estimateGas.maxPriorityFeePerGas)
+            .decimalPlaces(GWEI_PRECISION)
+            .toNumber()
+          estimateGas.maxFeePerGas.should.be.at.least(estimateGas.baseFee)
+          estimateGas.maxFeePerGas.should.be.at.equal(estimatedMaxFee)
+        }
+      })
+      it('should cache', async function () {
+        eipOracle = new GasPriceOracle({ shouldCache: true, chainId })
+        const estimateGasFirst: EstimatedGasPrice = await eipOracle.eip1559.estimateFees()
+
+        await sleep(2000)
+        const estimateGasSecond: EstimatedGasPrice = await eipOracle.eip1559.estimateFees()
+
+        if (estimateGasFirst?.maxFeePerGas) {
+          estimateGasFirst.maxFeePerGas.should.be.at.equal(estimateGasSecond?.maxFeePerGas)
+        }
+
+        await sleep(4000)
+        const estimateGasThird: EstimatedGasPrice = await eipOracle.eip1559.estimateFees()
+
+        if (estimateGasSecond?.maxFeePerGas) {
+          estimateGasSecond.maxFeePerGas.should.be.at.equal(estimateGasThird?.maxFeePerGas)
+        }
+      })
+    })
+  })
+})
+
+after('after', function () {
+  after(function () {
+    mockery.disable()
+    mockery.deregisterMock('node-fetch')
+  })
+})
--- a/src/tests/legacy.test.ts
+++ b/src/tests/legacy.test.ts
@@ -0,0 +1,383 @@
+/* eslint-disable @typescript-eslint/no-var-requires */
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-ignore
+import chai from 'chai'
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-ignore
+import mockery from 'mockery'
+import BigNumber from 'bignumber.js'
+import { before, describe } from 'mocha'
+
+import { sleep } from '@/utils'
+import { ChainId, NETWORKS } from '@/config'
+import { DEFAULT_TIMEOUT } from '@/constants'
+import { GasPriceOracle } from '@/services/gas-price-oracle'
+import { GasPrice, LegacyGasPriceOracle, OffChainOracle } from '@/services/legacy-gas-price'
+
+chai.use(require('chai-as-promised'))
+chai.should()
+
+let oracle = new GasPriceOracle()
+let { onChainOracles, offChainOracles } = oracle.legacy
+
+before('before', async () => {
+  const gasPrice = await oracle.legacy.gasPrices()
+  console.log('legacy gasPrice - ', { gasPrice })
+})
+
+before('before', function () {
+  const axiosMock = {
+    get: () => {
+      throw new Error('axios GET method is mocked for tests')
+    },
+    post: () => {
+      throw new Error('axios POST method is mocked for tests')
+    },
+  }
+  mockery.registerMock('axios', axiosMock)
+})
+
+beforeEach('beforeEach', function () {
+  oracle = new GasPriceOracle()
+  ;({ onChainOracles, offChainOracles } = oracle.legacy)
+})
+
+const INJECTED_RPC_URL = 'https://ethereum-rpc.trustwalletapp.com'
+
+describe('legacy gasOracle', function () {
+  describe('legacy constructor', function () {
+    it('should set default values', function () {
+      oracle.legacy.configuration.defaultRpc.should.be.equal(NETWORKS[ChainId.MAINNET].rpcUrl)
+      oracle.legacy.configuration.timeout.should.be.equal(DEFAULT_TIMEOUT)
+    })
+
+    it('should set passed values', function () {
+      const newOracle = new GasPriceOracle({ timeout: 1337 })
+
+      newOracle.legacy.configuration.defaultRpc.should.be.equal(NETWORKS[ChainId.MAINNET].rpcUrl)
+      newOracle.legacy.configuration.timeout.should.be.equal(1337)
+    })
+  })
+
+  describe('fetchGasPricesOffChain', function () {
+    it('should work', async function () {
+      const gas: GasPrice = await oracle.legacy.fetchGasPricesOffChain(true)
+
+      gas.instant.should.be.a('number')
+      gas.fast.should.be.a('number')
+      gas.standard.should.be.a('number')
+      gas.low.should.be.a('number')
+
+      gas.instant.should.be.at.least(gas.fast)
+      gas.fast.should.be.at.least(gas.standard)
+      gas.standard.should.be.at.least(gas.low)
+      gas.low.should.not.be.equal(0)
+    })
+
+    it('should throw if all offchain oracles are down', async function () {
+      mockery.enable({ useCleanCache: true, warnOnUnregistered: false })
+      const { GasPriceOracle } = require('../index')
+      oracle = new GasPriceOracle()
+      // @ts-ignore
+      await oracle.legacy.fetchGasPricesOffChain(true).should.be.rejectedWith('All oracles are down. Probably a network error.')
+      mockery.disable()
+    })
+  })
+
+  describe('fetchGasPricesOnChain', function () {
+    it('should work', async function () {
+      const gas: number = await oracle.legacy.fetchGasPricesOnChain()
+      gas.should.be.a('number')
+      gas.should.be.above(1)
+      gas.should.not.be.equal(0)
+    })
+
+    it('should work with custom rpc', async function () {
+      const rpc = INJECTED_RPC_URL
+      oracle = new GasPriceOracle({ defaultRpc: rpc })
+      oracle.legacy.configuration.defaultRpc.should.be.equal(rpc)
+      const gas: number = await oracle.legacy.fetchGasPricesOnChain()
+
+      gas.should.be.a('number')
+
+      gas.should.be.above(1)
+      gas.should.not.be.equal(0)
+    })
+
+    it('should remove oracle', async function () {
+      await oracle.legacy.fetchGasPricesOnChain()
+      oracle.legacy.removeOnChainOracle('chainlink')
+      // @ts-ignore
+      await oracle.legacy.fetchGasPricesOnChain().should.be.rejectedWith('All oracles are down. Probably a network error.')
+    })
+
+    it('should add oracle', async function () {
+      const toAdd = onChainOracles.chainlink
+      await oracle.legacy.fetchGasPricesOnChain()
+      oracle.legacy.removeOnChainOracle('chainlink')
+
+      // @ts-ignore
+      await oracle.legacy.fetchGasPricesOnChain().should.be.rejectedWith('All oracles are down. Probably a network error.')
+
+      oracle.legacy.addOnChainOracle(toAdd)
+      const gas: number = await oracle.legacy.fetchGasPricesOnChain()
+
+      gas.should.be.a('number')
+      gas.should.not.be.equal(0)
+    })
+
+    it('should throw if all onchain oracles are down', async function () {
+      mockery.enable({ useCleanCache: true, warnOnUnregistered: false })
+      const { GasPriceOracle } = require('../index')
+
+      oracle = new GasPriceOracle()
+      // @ts-ignore
+      await oracle.legacy.fetchGasPricesOnChain().should.be.rejectedWith('All oracles are down. Probably a network error.')
+      mockery.disable()
+    })
+  })
+
+  describe('fetchGasPriceFromRpc', function () {
+    it('should work', async function () {
+      const gas: number = await oracle.legacy.fetchGasPriceFromRpc()
+      gas.should.be.a('number')
+      gas.should.be.above(1)
+      gas.should.not.be.equal(0)
+    })
+
+    it('should work with custom rpc', async function () {
+      const rpc = INJECTED_RPC_URL
+      const oracle = new GasPriceOracle({ defaultRpc: rpc })
+      oracle.legacy.configuration.defaultRpc.should.be.equal(rpc)
+      const gas: number = await oracle.legacy.fetchGasPriceFromRpc()
+
+      gas.should.be.a('number')
+
+      gas.should.be.above(1)
+      gas.should.not.be.equal(0)
+    })
+
+    it('should throw if default rpc is down', async function () {
+      mockery.enable({ useCleanCache: true, warnOnUnregistered: false })
+      const { GasPriceOracle } = require('../index')
+
+      oracle = new GasPriceOracle()
+      // @ts-ignore
+      await oracle.legacy.fetchGasPriceFromRpc().should.be.rejectedWith('Default RPC is down. Probably a network error.')
+      mockery.disable()
+    })
+  })
+
+  describe('legacy gasPrice', function () {
+    it('should work', async function () {
+      const gas = (await oracle.gasPrices({ isLegacy: true })) as unknown as GasPrice
+
+      gas.instant.should.be.a('number')
+      gas.fast.should.be.a('number')
+      gas.standard.should.be.a('number')
+      gas.low.should.be.a('number')
+
+      gas.instant.should.be.at.least(gas.fast)
+      gas.fast.should.be.at.least(gas.standard)
+      gas.standard.should.be.at.least(gas.low)
+      gas.low.should.not.be.equal(0)
+    })
+
+    it('should fallback', async function () {
+      mockery.enable({ useCleanCache: true, warnOnUnregistered: false })
+      const { GasPriceOracle } = require('../index')
+
+      oracle = new GasPriceOracle()
+
+      const gas = (await oracle.gasPrices({ isLegacy: true })) as unknown as GasPrice
+
+      const shouldBe = LegacyGasPriceOracle.getMultipliedPrices(NETWORKS[ChainId.MAINNET].defaultGasPrice)
+
+      gas.instant.should.be.equal(shouldBe.instant)
+      gas.fast.should.be.equal(shouldBe.fast)
+      gas.standard.should.be.equal(shouldBe.standard)
+      gas.low.should.be.equal(shouldBe.low)
+
+      mockery.disable()
+    })
+
+    it('should fallback to set values', async function () {
+      mockery.enable({ useCleanCache: true, warnOnUnregistered: false })
+      const { GasPriceOracle } = require('../index')
+      oracle = new GasPriceOracle()
+
+      const fallbackGasPrices = {
+        gasPrices: {
+          instant: 50,
+          fast: 21,
+          standard: 10,
+          low: 3,
+        },
+      }
+      const gas = (await oracle.gasPrices({ isLegacy: true, fallbackGasPrices })) as unknown as GasPrice
+
+      gas.instant.should.be.equal(fallbackGasPrices.gasPrices.instant)
+      gas.fast.should.be.equal(fallbackGasPrices.gasPrices.fast)
+      gas.standard.should.be.equal(fallbackGasPrices.gasPrices.standard)
+      gas.low.should.be.equal(fallbackGasPrices.gasPrices.low)
+
+      mockery.disable()
+    })
+
+    it('should cache', async function () {
+      const oracle = new GasPriceOracle({ shouldCache: true })
+      const gasPricesFirst = await oracle.legacy.gasPrices()
+
+      await sleep(2000)
+      const gasPricesSecond = await oracle.legacy.gasPrices()
+
+      if (gasPricesFirst.fast) {
+        gasPricesFirst.fast.should.be.at.equal(gasPricesSecond?.fast)
+      }
+
+      await sleep(4000)
+      const gasPricesThird = await oracle.legacy.gasPrices()
+
+      if (gasPricesSecond.fast) {
+        gasPricesSecond.fast.should.be.at.equal(gasPricesThird?.fast)
+      }
+    })
+  })
+
+  describe('median', function () {
+    it('should work', function () {
+      const gas1 = { instant: 100, fast: 100, standard: 100, low: 100 }
+      const gas2 = { instant: 90, fast: 90, standard: 90, low: 90 }
+      const gas3 = { instant: 70, fast: 70, standard: 70, low: 70 }
+      const gas4 = { instant: 110.1, fast: 110.1, standard: 110.1, low: 110.1 }
+
+      let gas: GasPrice = LegacyGasPriceOracle.getMedianGasPrice([gas1, gas2, gas3])
+
+      gas.instant.should.be.a('number')
+      gas.fast.should.be.a('number')
+      gas.standard.should.be.a('number')
+      gas.low.should.be.a('number')
+
+      gas.instant.should.be.eq(90)
+      gas.fast.should.be.eq(90)
+      gas.standard.should.be.eq(90)
+      gas.low.should.be.eq(90)
+
+      gas = LegacyGasPriceOracle.getMedianGasPrice([gas1, gas2, gas3, gas4])
+
+      gas.instant.should.be.a('number')
+      gas.fast.should.be.a('number')
+      gas.standard.should.be.a('number')
+      gas.low.should.be.a('number')
+
+      gas.instant.should.be.eq(95)
+      gas.fast.should.be.eq(95)
+      gas.standard.should.be.eq(95)
+      gas.low.should.be.eq(95)
+    })
+  })
+
+  describe('fetchMedianGasPriceOffChain', function () {
+    it('should work', async function () {
+      const gas: GasPrice = await oracle.legacy.fetchMedianGasPriceOffChain()
+
+      gas.instant.should.be.a('number')
+      gas.fast.should.be.a('number')
+      gas.standard.should.be.a('number')
+      gas.low.should.be.a('number')
+
+      gas.instant.should.be.at.least(gas.fast)
+      gas.fast.should.be.at.least(gas.standard)
+      gas.standard.should.be.at.least(gas.low)
+      gas.low.should.not.be.equal(0)
+    })
+  })
+
+  describe('normalize result values', function () {
+    const wrongDecimalsGas = {
+      gasPrices: {
+        instant: 1.1,
+        fast: 2.12345678901,
+        standard: 3.12345678901,
+        low: 3.12345679,
+      },
+    }
+
+    const checkDecimals = (gas: GasPrice) => {
+      const gasPrices: number[] = Object.values(gas)
+
+      for (const gas of gasPrices) {
+        new BigNumber(gas).dp().should.be.at.most(9)
+      }
+    }
+
+    it('default fallback should be normalized', function () {
+      mockery.enable({ useCleanCache: true, warnOnUnregistered: false })
+
+      oracle = new GasPriceOracle({ fallbackGasPrices: wrongDecimalsGas })
+
+      checkDecimals(oracle.legacy.configuration.fallbackGasPrices)
+
+      mockery.disable()
+    })
+
+    it('fallback should be normalized', async function () {
+      mockery.enable({ useCleanCache: true, warnOnUnregistered: false })
+      const { GasPriceOracle } = require('../index')
+
+      oracle = new GasPriceOracle()
+
+      const gas = await oracle.legacy.gasPrices(wrongDecimalsGas.gasPrices)
+
+      checkDecimals(gas)
+      mockery.disable()
+    })
+
+    it('rpc fallback should be normalized', async function () {
+      oracle = new GasPriceOracle({ chainId: 42161, defaultRpc: 'https://arb1.arbitrum.io/rpc' })
+
+      const gas = await oracle.legacy.gasPrices()
+
+      checkDecimals(gas)
+    })
+  })
+
+  describe('askOracle', function () {
+    const chains = Object.keys(NETWORKS).map((id) => Number(id))
+
+    chains.forEach((chainId) => {
+      describe(`all ${ChainId[chainId]} oracles should answer`, function () {
+        oracle = new GasPriceOracle({ chainId })
+        ;({ offChainOracles } = oracle.legacy)
+
+        for (const o of Object.values(offChainOracles) as OffChainOracle[]) {
+          it(`check ${o.name}`, async function () {
+            try {
+              const gas: GasPrice = await oracle.legacy.askOracle(o)
+
+              gas.instant.should.be.a('number')
+              gas.fast.should.be.a('number')
+              gas.standard.should.be.a('number')
+              gas.low.should.be.a('number')
+
+              gas.instant.should.be.at.least(gas.fast)
+              gas.fast.should.be.at.least(gas.standard)
+              gas.standard.should.be.at.least(gas.low)
+              gas.low.should.not.be.equal(0)
+            } catch (e) {
+              console.error(`Failed to get data from ${o.name} oracle`)
+              throw new Error(e)
+            }
+          })
+        }
+      })
+    })
+  })
+})
+
+after('after', function () {
+  after(function () {
+    mockery.disable()
+    mockery.deregisterMock('node-fetch')
+  })
+})
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,24 +1,40 @@
-export type OffChainOracle = {
-  name: string;
-  url: string;
-  instantPropertyName: string;
-  fastPropertyName: string;
-  standardPropertyName: string;
-  lowPropertyName: string;
-  denominator: number;
-};
+import { AllOracles } from './services/legacy-gas-price'

-export type OnChainOracle = {
-  name: string;
-  rpc?: string;
-  contract: string;
-  callData: string;
-  denominator: string;
-};
+export interface Block {
+  baseFeePerGas: string
+  difficulty: string
+  extraData: string
+  gasLimit: string
+  gasUsed: string
+  hash: string
+  miner: string
+  mixHash: string
+  nonce: string
+  number: string
+  parentHash: string
+  receiptsRoot: string
+  sha3Uncles: string
+  size: string
+  stateRoot: string
+  timestamp: string
+  totalDifficulty: string
+  transactions: unknown[]
+  transactionsRoot: string
+  uncles: unknown[]
+}

-export type GasPrice = {
-  instant: number;
-  fast: number;
-  standard: number;
-  low: number;
-};
+export interface FeeHistory {
+  baseFeePerGas: string[]
+  gasUsedRatio: number[]
+  reward?: string[][]
+  oldestBlock: string
+}
+
+export type NetworksConfig = {
+  oracles: AllOracles
+  rpcUrl: string
+  defaultGasPrice: number
+  maxGasPrice: number
+  blocksCount: number
+  percentile: number
+}
--- a/src/utils/crypto.ts
+++ b/src/utils/crypto.ts
@@ -0,0 +1,20 @@
+import BigNumber from 'bignumber.js'
+import { GWEI, GWEI_PRECISION } from '@/constants'
+
+const toGwei = (amount: number | string | BigNumber): BigNumber => {
+  return new BigNumber(amount).multipliedBy(GWEI).decimalPlaces(GWEI_PRECISION)
+}
+
+const fromWeiToGwei = (amount: number | string | BigNumber): BigNumber => {
+  return new BigNumber(amount).dividedBy(GWEI).decimalPlaces(GWEI_PRECISION)
+}
+
+const fromNumberToHex = (amount: number | string | BigNumber): string => {
+  return `0x${new BigNumber(amount).toString(16)}`
+}
+
+const fromGweiToWeiHex = (value: number): string => {
+  return fromNumberToHex(new BigNumber(value).multipliedBy(GWEI).decimalPlaces(0))
+}
+
+export { toGwei, fromWeiToGwei, fromGweiToWeiHex, fromNumberToHex }
--- a/src/utils/index.ts
+++ b/src/utils/index.ts
@@ -0,0 +1,8 @@
+export * from './math'
+export * from './crypto'
+
+const sleep = (time: number): Promise<boolean> => {
+  return new Promise((res) => setTimeout(() => res(true), time))
+}
+
+export { sleep }
--- a/src/utils/math.ts
+++ b/src/utils/math.ts
@@ -0,0 +1,45 @@
+import BigNumber from 'bignumber.js'
+
+import { BG_ZERO, PERCENT_MULTIPLIER } from '@/constants'
+
+import { toGwei } from './crypto'
+
+type FindMaxRes = {
+  highest: BigNumber
+  index: number
+}
+
+const findMax = (values: BigNumber[]): FindMaxRes => {
+  return values.reduce(
+    (acc, curr, index) => {
+      const isGreaterThanAcc = curr.isGreaterThan(acc.highest)
+      if (isGreaterThanAcc) {
+        acc.highest = curr
+        acc.index = index
+      }
+      return acc
+    },
+    {
+      highest: BG_ZERO,
+      index: 0,
+    },
+  )
+}
+
+const getMedian = <T>(arr: T[]): number => {
+  return Math.floor(arr.length / 2)
+}
+
+const round = (value: number | string | BigNumber): BigNumber => {
+  return new BigNumber(value).decimalPlaces(0, 2)
+}
+
+const roundGwei = (value: number | string | BigNumber): BigNumber => {
+  return toGwei(value).decimalPlaces(0, 2)
+}
+
+const bumpOnPercent = (value: number, bumpPercent: number): number => {
+  return value + (value * bumpPercent) / PERCENT_MULTIPLIER
+}
+
+export { findMax, getMedian, round, roundGwei, bumpOnPercent }
--- a/tests/index.test.ts
+++ b/tests/index.test.ts
@@ -1,149 +0,0 @@
-import { GasPrice } from '../src/types';
-import mockery from 'mockery';
-import chai from 'chai';
-import { onChainOracles } from '../src/config';
-
-const { GasPriceOracle } = require('../src/index');
-chai.use(require('chai-as-promised'));
-chai.should();
-let oracle = new GasPriceOracle();
-
-before('before', function () {
-  let fetchMock = () => {
-    throw new Error('Mocked for tests');
-  };
-  mockery.registerMock('node-fetch', fetchMock);
-});
-
-beforeEach('beforeEach', function () {
-  oracle = new GasPriceOracle();
-});
-
-describe('fetchGasPricesOffChain', function () {
-  it('should work', async function () {
-    const gas: GasPrice = await oracle.fetchGasPricesOffChain();
-
-    gas.instant.should.be.a('number');
-    gas.fast.should.be.a('number');
-    gas.standard.should.be.a('number');
-    gas.low.should.be.a('number');
-
-    gas.instant.should.be.above(gas.fast);
-    gas.fast.should.be.above(gas.standard);
-    gas.standard.should.be.above(gas.low);
-    gas.low.should.not.be.equal(0);
-  });
-
-  it('should throw if all offchain oracles are down', async function () {
-    mockery.enable({ useCleanCache: true, warnOnUnregistered: false });
-    const { GasPriceOracle } = require('../src/index');
-    oracle = new GasPriceOracle();
-    await oracle.fetchGasPricesOffChain().should.be.rejectedWith('All oracles are down. Probaly network error.');
-    mockery.disable();
-  });
-
-  it('should not throw if throwIfFailsToFetch is false', async function () {
-    mockery.enable({ useCleanCache: true, warnOnUnregistered: false });
-    const { GasPriceOracle } = require('../src/index');
-    oracle = new GasPriceOracle();
-    await oracle.fetchGasPricesOffChain(false);
-    mockery.disable();
-  });
-});
-
-describe('fetchGasPricesOnChain', function () {
-  it('should work', async function () {
-    const gas: GasPrice = await oracle.fetchGasPricesOnChain();
-
-    gas.instant.should.be.a('number');
-    gas.fast.should.be.a('number');
-    gas.standard.should.be.a('number');
-    gas.low.should.be.a('number');
-
-    gas.instant.should.be.above(gas.fast);
-    gas.fast.should.be.above(gas.standard);
-    gas.standard.should.be.above(gas.low);
-    gas.low.should.not.be.equal(0);
-  });
-
-  it('should work with custom rpc', async function () {
-    const rpc = 'https://ethereum-rpc.trustwalletapp.com';
-    const oracle = new GasPriceOracle(rpc);
-    oracle.defaultRpc.should.be.equal(rpc);
-    const gas: GasPrice = await oracle.fetchGasPricesOnChain();
-
-    gas.instant.should.be.a('number');
-    gas.fast.should.be.a('number');
-    gas.standard.should.be.a('number');
-    gas.low.should.be.a('number');
-
-    gas.instant.should.be.above(gas.fast);
-    gas.fast.should.be.above(gas.standard);
-    gas.standard.should.be.above(gas.low);
-    gas.low.should.not.be.equal(0);
-  });
-
-  it('should remove oracle', async function () {
-    await oracle.fetchGasPricesOnChain();
-    oracle.removeOnChainOracle('chainlink');
-    await oracle.fetchGasPricesOnChain().should.be.rejectedWith('All oracles are down. Probaly network error.');
-  });
-
-  it('should add oracle', async function () {
-    const { chainlink } = onChainOracles;
-    await oracle.fetchGasPricesOnChain();
-    oracle.removeOnChainOracle('chainlink');
-    await oracle.fetchGasPricesOnChain().should.be.rejectedWith('All oracles are down. Probaly network error.');
-    oracle.addOnChainOracle(chainlink);
-    const gas: GasPrice = await oracle.fetchGasPricesOnChain();
-
-    gas.instant.should.be.a('number');
-    gas.fast.should.be.a('number');
-    gas.standard.should.be.a('number');
-    gas.low.should.be.a('number');
-
-    gas.instant.should.be.above(gas.fast);
-    gas.fast.should.be.above(gas.standard);
-    gas.standard.should.be.above(gas.low);
-    gas.low.should.not.be.equal(0);
-  });
-
-  it('should throw if all onchain oracles are down', async function () {
-    mockery.enable({ useCleanCache: true, warnOnUnregistered: false });
-    const { GasPriceOracle } = require('../src/index');
-    oracle = new GasPriceOracle();
-    await oracle.fetchGasPricesOnChain().should.be.rejectedWith('All oracles are down. Probaly network error.');
-    mockery.disable();
-  });
-
-  it('should not throw if throwIfFailsToFetch is false', async function () {
-    mockery.enable({ useCleanCache: true, warnOnUnregistered: false });
-    const { GasPriceOracle } = require('../src/index');
-    oracle = new GasPriceOracle();
-    await oracle.fetchGasPricesOnChain(false);
-    mockery.disable();
-  });
-});
-
-describe('gasPrice', function () {
-  it('should work', async function () {
-    const gas: GasPrice = await oracle.gasPrices();
-
-    gas.instant.should.be.a('number');
-    gas.fast.should.be.a('number');
-    gas.standard.should.be.a('number');
-    gas.low.should.be.a('number');
-
-    gas.instant.should.be.above(gas.fast);
-    gas.fast.should.be.above(gas.standard);
-    gas.standard.should.be.above(gas.low);
-    gas.low.should.not.be.equal(0);
-  });
-});
-
-after('after', function () {
-  after(function () {
-    mockery.disable();
-    mockery.deregisterMock('node-fetch');
-  });
-});
--- a/tsconfig.esm.json
+++ b/tsconfig.esm.json
@@ -0,0 +1,9 @@
+{
+  "extends": "./tsconfig",
+  "compilerOptions": {
+    "declaration": false,
+    "target": "es2015",
+    "module": "es2015",
+    "outDir": "lib/esm"
+  }
+}
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,71 +1,33 @@
 {
  "compilerOptions": {
-    /* Basic Options */
-    "target": "es2017" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */,
-    "module": "commonjs" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */,
-    "lib": [
-      "es2017",
-      "esnext.asynciterable",
-      "es2019"
-      ] /* Specify library files to be included in the compilation. */,
-    "outDir": "./lib",                        /* Redirect output structure to the directory. */
-    "strict": true /* Enable all strict type-checking options. */,
-    "strictPropertyInitialization": false /* Enable strict checking of property initialization in classes. */,
-    "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
-    "declaration": true,                   /* Generates corresponding '.d.ts' file. */
-    // "allowJs": true,                       /* Allow javascript files to be compiled. */
-    // "checkJs": true,                       /* Report errors in .js files. */
-    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
-    // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
-    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
-    // "outFile": "./",                       /* Concatenate and emit output to single file. */
-    // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
-    // "composite": true,                     /* Enable project compilation */
-    // "removeComments": true,                /* Do not emit comments to output. */
-    // "noEmit": true,                        /* Do not emit outputs. */
-    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
-    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
-    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
-
-    /* Strict Type-Checking Options */
-    // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
-    // "strictNullChecks": true,              /* Enable strict null checks. */
-    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
-    // "strictBindCallApply": true,           /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
-    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
-    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
-
-    /* Additional Checks */
-    // "noUnusedLocals": true,                /* Report errors on unused locals. */
-    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
-    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
-    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
-
-    /* Module Resolution Options */
-    // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
-    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
-    // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
-    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
-    // "typeRoots": [],                       /* List of folders to include type definitions from. */
-    // "types": [],                           /* Type declaration files to be included in compilation. */
-    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
-    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
-
-    /* Source Map Options */
-    // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */
-    // "mapRoot": "",                         /* Specify the location where debugger should locate map files instead of generated locations. */
-    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
-    // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
-
-    /* Experimental Options */
-    "experimentalDecorators": true /* Enables experimental support for ES7 decorators. */,
-    "emitDecoratorMetadata": true /* Enables experimental support for emitting type metadata for decorators. */,
-    "plugins": [
-      {
-        "name": "typescript-tslint-plugin"
-      }
-    ]
+    "target": "es5",
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "lib": ["es5", "es6", "es2021", "esnext"],
+    "experimentalDecorators": true,
+    "sourceMap": true,
+    "outDir": "lib",
+    "noImplicitAny": true,
+    "allowJs": true,
+    "declaration": true,
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "checkJs": false,
+    "noUnusedLocals": true,
+    "strictNullChecks": true,
+    "noImplicitThis": true,
+    "noImplicitReturns": true,
+    "allowSyntheticDefaultImports": true,
+    "strictFunctionTypes": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "baseUrl": ".",
+    "paths": {
+      "@/*": ["./src/*"]
    },
-  "include": ["src"],
-  "exclude": ["node_modules", "tests"]
+    "types": ["@types/node"]
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "src/tests"]
 }
--- a/tslint.json
+++ b/tslint.json
@@ -1,10 +0,0 @@
-{
-  "extends": "tslint-config-standard",
-  "defaultSeverity": "error",
-  "rules": {
-    "semicolon": [true, "always"],
-    "space-before-function-paren": [true, {"anonymous": "always", "named": "never", "asyncArrow": "always"}],
-    "type-literal-delimiter": true
-  }
-}
-
--- a/yarn.lock
+++ b/yarn.lock
Author	SHA1	Message	Date
Pasha8914	06b380b488	feat: cached gas prices	2022-08-18 23:17:00 +10:00
Pavel Khavilov	e9bfc10588	Refactor and features (#17 ) * feat: features and refactor * fixed return types * update README Co-authored-by: Danil Kovtonyuk <danx.kov@gmail.com>	2022-07-11 16:57:38 +10:00
Danil Kovtonyuk	85ca7000bc	remove Avalanche	2022-05-23 20:26:11 +10:00
Danil Kovtonyuk	d65b3dfe6c	remove Arbitrum	2022-04-13 21:30:55 +10:00
Danil Kovtonyuk	be905f2b71	fix: mainnet oracles	2022-03-18 05:19:29 +10:00
Danil Kovtonyuk	4373641a30	fix: normalize result values	2021-11-16 03:46:43 +10:00
Danil Kovtonyuk	76f8cb036d	fix: default values	2021-11-16 01:51:22 +10:00
Danil Kovtonyuk	64c5a68639	fix: update dependencies	2021-11-15 16:39:20 +10:00
dependabot[bot]	1dbd778166	Bump axios from 0.19.2 to 0.21.2 Bumps [axios](https://github.com/axios/axios) from 0.19.2 to 0.21.2. - [Release notes](https://github.com/axios/axios/releases) - [Changelog](https://github.com/axios/axios/blob/master/CHANGELOG.md) - [Commits](https://github.com/axios/axios/compare/v0.19.2...v0.21.2) --- updated-dependencies: - dependency-name: axios dependency-type: direct:production ... Signed-off-by: dependabot[bot] <support@github.com>	2021-11-15 16:38:05 +10:00
dependabot[bot]	47089200af	Bump glob-parent from 5.1.1 to 5.1.2 Bumps [glob-parent](https://github.com/gulpjs/glob-parent) from 5.1.1 to 5.1.2. - [Release notes](https://github.com/gulpjs/glob-parent/releases) - [Changelog](https://github.com/gulpjs/glob-parent/blob/main/CHANGELOG.md) - [Commits](https://github.com/gulpjs/glob-parent/compare/v5.1.1...v5.1.2) --- updated-dependencies: - dependency-name: glob-parent dependency-type: indirect ... Signed-off-by: dependabot[bot] <support@github.com>	2021-11-15 16:37:53 +10:00
dependabot[bot]	4cf2521880	Bump lodash from 4.17.20 to 4.17.21 Bumps [lodash](https://github.com/lodash/lodash) from 4.17.20 to 4.17.21. - [Release notes](https://github.com/lodash/lodash/releases) - [Commits](https://github.com/lodash/lodash/compare/4.17.20...4.17.21) Signed-off-by: dependabot[bot] <support@github.com>	2021-11-15 16:37:41 +10:00
dependabot[bot]	cd5bca4963	Bump y18n from 4.0.0 to 4.0.1 Bumps [y18n](https://github.com/yargs/y18n) from 4.0.0 to 4.0.1. - [Release notes](https://github.com/yargs/y18n/releases) - [Changelog](https://github.com/yargs/y18n/blob/master/CHANGELOG.md) - [Commits](https://github.com/yargs/y18n/commits) Signed-off-by: dependabot[bot] <support@github.com>	2021-11-15 16:37:19 +10:00
Danil Kovtonyuk	6be967e8c9	fix: update oracles	2021-11-15 16:31:41 +10:00
Danil Kovtonyuk	b13a4252ab	feat: add fetch gas price from rpc	2021-10-05 11:47:34 +03:00
Danil Kovtonyuk	5036c65643	add xDAI	2021-08-25 22:31:20 +10:00
Danil Kovtonyuk	89a69519b2	fix: test	2021-08-17 17:14:50 +10:00
Danil Kovtonyuk	3fce50efbb	fix: constructor	2021-08-17 17:04:01 +10:00
Danil Kovtonyuk	9b0c229ace	add polygon	2021-06-15 13:26:02 +03:00
Danil Kovtonyuk	a508e41652	fix: bscgas property	2021-06-10 23:33:59 +03:00
Danil Kovtonyuk	bb58318b6f	add defaultFallbackGasPrices option	2021-06-03 15:16:49 +03:00
Danil Kovtonyuk	32c256bc4e	update readme	2021-06-03 13:01:25 +03:00
Danil Kovtonyuk	efd3cb3c7c	fix test	2021-06-03 12:51:14 +03:00
Danil Kovtonyuk	88a757bb45	bump version	2021-06-03 12:46:36 +03:00
Danil Kovtonyuk	c30c7aed63	add binance	2021-06-03 12:46:36 +03:00
Alexey	ca24732a9b	fix bug with extra precision	2020-10-20 18:11:07 +03:00
Alexey	a05a1e62d4	anyblock new oracle	2020-10-20 17:39:50 +03:00
Alexey	4c6acfd559	bump version	2020-10-19 21:06:18 +03:00
Roman Storm	bd010c360b	Merge pull request #2 from peppersec/median Version 0.2	2020-10-19 11:04:20 -07:00
Alexey	9bd9a3b165	eslint - dont be quiet. Fix warnings	2020-10-19 16:14:07 +03:00
Alexey	a2a4e67845	gasnow gas price orace	2020-10-19 16:08:19 +03:00
Alexey	092d863bd2	fix eslint command	2020-10-19 16:07:56 +03:00
Alexey	edc9b377a6	fix link	2020-10-19 15:16:34 +03:00
Alexey	bb8dc28075	update readme	2020-10-19 15:15:25 +03:00
Alexey	305072f198	remove tslint (using eslint now)	2020-10-19 15:02:47 +03:00
Alexey	402732a84b	parallel requests for median aproach	2020-10-17 02:07:39 +03:00
Alexey	8d86bfc0fc	median gas price init	2020-10-16 19:34:59 +03:00
Alexey	b39073aa53	fix CI	2020-10-16 14:13:31 +03:00
Alexey	0b706b704f	prettier + wordings	2020-10-16 14:10:25 +03:00
Alexey	8a21dcd282	bump version	2020-08-12 12:57:08 +03:00
Alexey	d3b942fdc7	fix tests	2020-08-12 12:53:43 +03:00
Alexey	4f346472c3	fix publish action	2020-08-12 12:37:51 +03:00
Roman Storm	c2584615d2	Merge pull request #1 from peppersec/dependabot/npm_and_yarn/lodash-4.17.19 Bump lodash from 4.17.15 to 4.17.19	2020-08-11 17:37:55 -07:00
Roman Storm	c24202608e	update onchain oracle	2020-08-11 17:36:37 -07:00
dependabot[bot]	b029bcc89b	Bump lodash from 4.17.15 to 4.17.19 Bumps [lodash](https://github.com/lodash/lodash) from 4.17.15 to 4.17.19. - [Release notes](https://github.com/lodash/lodash/releases) - [Commits](https://github.com/lodash/lodash/compare/4.17.15...4.17.19) Signed-off-by: dependabot[bot] <support@github.com>	2020-07-20 21:50:35 +00:00
Alexey	5c28cc6025	fix test	2020-06-04 18:49:16 +03:00
Alexey	4548e6badb	switch to axios	2020-06-04 18:45:33 +03:00
Alexey	82b6650a1c	update build shield	2020-06-04 10:16:04 +03:00
poma	4db4d8cf93	add CI and npm publish	2020-06-04 05:48:35 +03:00
Roman Storm	1be22264cd	update	2020-06-03 16:08:09 -07:00
Roman Storm	2b355c5da1	Create LICENSE	2020-06-03 14:11:01 -07:00