_section: Provider API Keys @<api-keys>

//( **TL; DR** &ndash; sign up for your own API keys with the links below to improve your application performance )//

When using a [[Provider]] backed by an API service (such as [[link-alchemy]],
[[link-etherscan]] or [[link-infura]]), the service requires an API key,
which allows each service to track individual projects and their usage and
permissions.

The ethers library offers default API keys for each service, so that each
[[Provider]] works out-of-the-box.

These API keys are a provided as a community resource by the backend services
for low-traffic projects and for early prototyping.

Since these API keys are shared by all users (that have not acquired their
own API key), they are aggressively throttled which means reties occur more
frequently and the responses are slower.

It is **highly recommended** that you sign up for a free API key from each service for their
free tier, which (depending on the service) includes many advantages:

- a much **higher request rate** and concurrent request limit
- **faster** responses with fewer retries and timeouts
- useful **metric tracking** for performance tuning and to analyze your customer behaviour
- more **advanced APIs**, such as archive data or advanced log queries

_subsection: Etherscan @<api-keys--etherscan>

Etherscan is an Ethereum block explorer, which is possibly the most useful
developer tool for building and debugging Ethereum applications.

They offer an extensive collection of API endpoints which provide all the
operations required to interact with the Ethereum Blockchain.

[Sign up for a free API key on Etherscan](link-etherscan-signup)

**Benefits:**

- higher rate limit (since you are not using the [shared rate limit](link-etherscan-ratelimit))
- customer usage metrics

_subsection: INFURA @<api-keys--infura>

The INFURA service has been around for quite some time and is very robust
and reliable and highly recommend.

They offer a standard JSON-RPC interface and a WebSocket interface, which makes
interaction with standard tools versatile, simple and straight forward.

[Sign up for a free Project ID on INFURA](link-infura-signup)

**Benefits:**

- higher rate limit
- customer usage metrics
- access to archive data (requires paid upgrade)

_subsection: Alchemy @<api-keys--alchemy>

The Alchemy service has been around a few years and is also very robust
and reliable.

They offer a standard JSON-RPC interface and a WebSocket interface, as well
as a collection of advanced APIs for interacting with tokens and to assist
with debugging.

[Sign up for a free API key on Alchemy](link-alchemy-signup)

**Benefits:**

- higher rate limit
- customer usage metrics
- access to advanced token balance and metadata APIs
- access to advanced debugging trace and revert reason APIs


_subsection: Creating a Default Provider @<api-keys--getDefaultProvider>

The [default provider](providers-getDefaultProvider) connects to multiple
backends and verifies their results internally, making it simple to have
a high level of trust in third-party services.

A second optional parameter allows API keys to be specified to each
Provider created internally and any API key omitted will fallback onto
using the default API key for that service.

It is **highly recommended** that you provide an API for each service, to
maximize your applications performance.

_code: Passing API Keys into getDefaultProvider @lang<script>

// Use the mainnet
const network = "homestead";

// Specify your own API keys
// Each is optional, and if you omit it the default
// API key for that service will be used.
const provider = ethers.getDefaultProvider(network, {
    etherscan: YOUR_ETHERSCAN_API_KEY,
    infura: YOUR_INFURA_PROJECT_ID,
    alchemy: YOUR_ALCHEMY_API_KEY
});