> ## Documentation Index
> Fetch the complete documentation index at: https://nango.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Rate limits

> Guide on how to handle API rate limits from external APIs.

External APIs often enforce rate limits to prevent excessive use. When these limits are reached, you'll start receiving HTTP `429 Too Many Requests` errors, blocking further requests until the limit resets.

To maintain data freshness and avoid disruptions in your integration functions, it's crucial to manage your API call volume and handle rate limits effectively. Nango simplifies this process significantly.

## Strategy 1: Retry with exponential backoff

The simplest strategy involves retrying failed requests after waiting:

When you configure HTTP requests using Nango's helper ([reference](/reference/functions/functions-sdk#http-requests)), you can specify the number of retries:

```ts theme={null}
await nango.get({ endpoint: '/some-endpoint', retries: 10 });
```

This configuration enables automatic retries on receiving a `429` status code, with the retries spaced out using exponential backoff. This method is efficient because:

* It uses exponential backoff to wait out the rate-limit period
* Nango [sync functions](/guides/functions/syncs/sync-functions) can run for up to 24 hours, allowing retries to occur within this window (note that action functions and webhook functions have shorter lifespans; see [Resource limits](/guides/platform/limits))
* It works for APIs without requiring any API-specific configurations

Find details about HTTP request retries in the [reference](/reference/functions/functions-sdk#http-request-retries).

## Strategy 2: Leverage rate-limit headers

Most of the time, the first strategy is sufficient to handle rate limits.

For APIs with stringent limits, Nango provides a more refined and customized approach by automatically parsing API-specific rate-limit headers from responses and scheduling retries only after the rate limit period has reset:

This is set up in the same way as the first strategy:

```ts theme={null}
await nango.get({ endpoint: '/some-endpoint', retryHeader: { at: "x-ratelimit-reset" } });
```

If rate-limit headers are not already configured for an API you are using, you can request their inclusion by reaching out to the Nango team via the [community](https://nango.dev/slack)—typically within 24 hours.

## Related guides

* [Sync efficiency](/guides/functions/syncs/sync-efficiency) - avoid unnecessary provider requests.
* [Action functions](/guides/functions/action-functions) - design retries for idempotent actions.
* [Resource limits](/guides/platform/limits) - understand runtime constraints.
* [Functions SDK reference](/reference/functions/functions-sdk#http-request-retries) - configure request retries.

<Tip>
  **Questions, problems, feedback?** Please reach out in the [Slack community](https://nango.dev/slack).
</Tip>