304 Not Modified

What 304 Not Modified means {#what}

The response to a conditional GET request where the resource hasn’t changed since the client last fetched it. No body is sent — the client should use its cached version. A key building block of HTTP caching.

When you’ll see a 304 {#when}

• Browser requesting a resource it already has cached
• Client sending If-Modified-Since or If-None-Match headers

When to use 304 {#use}

• Implement ETags and Last-Modified headers to enable conditional requests
• Significant bandwidth and performance savings for static assets and APIs