# 304 Not Modified

> Instructs the client that the cached version of the resource is still valid.

Source: https://apiguide.dev/status-codes/304
Class: redirection
Defined in: RFC 9110, Section 15.4.5 <https://www.rfc-editor.org/rfc/rfc9110.html#section-15.4.5>
Updated: 2026-07-09

## What does HTTP status code 304 mean?

The 304 Not Modified status code indicates that the resource has not changed since the last request, so the server is not sending a response body. The client can safely use its cached copy.

## When to use it in APIs

Used for HTTP caching. The client sends conditional headers like `If-None-Match` (containing an ETag) or `If-Modified-Since`. If the server detects no changes, it returns a 304.

## How it compares to other codes

* **200 OK**: Returns the full payload, whereas 304 returns no body to conserve bandwidth.