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

# Rate limiting

> Rate limiting is used to prevent the frequency of an operation from exceeding some constraint, thus being crucial to the timely handling of all critical requests.


***

To maximize your Experience, Chameleon sets very high limits on the number of total requests and the amount of concurrency we support. At this time enforce rate limiting as such:

* Global across all endpoints.
* [User Profile Searching](/apis/profiles-search) with `max_concurrent=1` or in situations where the API is being used abusively.
* [Creating a Delivery](/apis/deliveries) with `max_concurrent=1` per User Profile to handle the enforcement of the maximum [Pending Deliveries](/apis/deliveries#limits).

There are a few possible strategies for rate limiting:

* The `global` strategy is applied to all requests with limited exceptions. Currently set to 60-120 requests per minute.
* The `max_concurrent` strategy is used to limit based on the **maximum concurrent requests.** When limiting with this strategy, we subtract and add from an N-sized bucket. We give an `X-RateLimit-Limit` header with N number of concurrent requests when that limit is reached. Please wait until at least one of the outstanding requests finishes. This strategy will queue for up to 4 seconds to allow other concurrent requests to complete. If no request completes during that initial 4 second wait, a 429 response will be sent.
* The `bucket` strategy is used to limit based on the **total number of requests**. Using this strategy, the bucket window expires after N seconds. We give an `X-Ratelimit-Wait` header with N number of seconds. This is the number of seconds to pause for until requests can proceed without immediate rate limiting.

> Contact us to speak about [Changing these limits](https://app.chameleon.io/help).

| Strategy        | Header              | Example value | description                                                                                                  |
| --------------- | ------------------- | ------------- | ------------------------------------------------------------------------------------------------------------ |
| global          | `X-Retry-After`     | `19`          | Up to N requests can occur per minute. Wait for at least `19` seconds before sending your next request.      |
| max\_concurrent | `X-Ratelimit-Limit` | `4`           | Up to N requests can be "running" at the same time. Wait for at least 1 request to complete before retrying. |
| bucket          | `X-Ratelimit-Wait`  | `12`          | Up to N requests can have started within the time window. Pause for N seconds before retrying your request.  |

#### HTTP Response

When enforcing rate limiting, both a header and a response body will give you information.

```text theme={null}
X-Ratelimit-Wait: 12
```

```json theme={null}
{
  "code": 429,
  "messages": ["Rate Limited: Please refer to the API docs https://developers.chameleon.io/concepts/rate-limiting for more information"],
  "wait": 12
}
```

```text theme={null}
X-Ratelimit-Limit: 4
```

```json theme={null}
{
  "code": 429,
  "messages": ["Rate Limited: Please refer to the API docs https://developers.chameleon.io/concepts/rate-limiting for more information"],
  "limit": 4
}
```