# Performance

## Rate Limits

To ensure API stability against bursts of traffic the Zocdoc API limits the number of requests a developer can make. Rate limited requests will fail with an HTTP status code of `429` and developers should use exponential backoff to reduce their request rate. On a case by case basis these limits may be reduced without notice to prevent abuse or increased to accomodate high traffic applications.

## Request and Response Compression

In order to improve the performance of HTTP requests, the Zocdoc API supports optional [gzip compression](https://developer.mozilla.org/en-US/docs/Glossary/gzip_compression) on both the request and response body.

To send a [compressed request body](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Encoding), use gzip compression to compress the request body, then add the `Content-Encoding: gzip` header to the request.

To receive a [compressed response body](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Accept-Encoding), add the `Accept-Encoding: gzip` header to your request, then unzip the response body of the content.

Many browsers and http client libraries automatically add these headers, so check to see if your library supports it automatically or easily.