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

# API rate limits, quotas, and throttling headers

> Understand OMOPHub API rate limits per plan, how to read throttling response headers, and how to request higher quotas for production workloads.

The response headers describe your current rate limit following every request in conformance with the [IETF standard](https://datatracker.ietf.org/doc/html/draft-ietf-httpapi-ratelimit-headers):

| Header name           | Description                                                         |
| --------------------- | ------------------------------------------------------------------- |
| `ratelimit-limit`     | Maximum number of requests allowed within a window.                 |
| `ratelimit-remaining` | How many requests you have left within the current window.          |
| `ratelimit-reset`     | How many seconds until the limits are reset.                        |
| `ratelimit-window`    | The window size in seconds for the rate limit.                      |
| `retry-after`         | How many seconds you should wait before making a follow-up request. |

## Rate Limit Responses

The default maximum rate limit is 2 requests per second. This number can be increased upon request.

After that, you’ll hit the rate limit and receive a 429 response error code. You can find all 429 responses by filtering for 429 at the OMOPHub Logs page.

To prevent this, we recommend reducing the rate at which you request the API.
This can be done by introducing a queue mechanism or reducing the number of concurrent requests per second.

If you have specific requirements, [contact support](https://omophub.com/contact) to request a rate increase.