Cache-Control

Cache-Control is an HTTP header, sent in responses and requests, that defines caching directives. Values like max-age, no-store, no-cache and public tell browsers and shared caches how to treat a response.

Why it matters

The header directly controls speed and freshness. Long lifetimes on static files make repeat visits fast and reduce bandwidth, while short or no caching on dynamic or private pages prevents stale or leaked data.

You can read the header on any URL with a response header inspector; CDNs may add or override it, so test the final response a visitor receives, not just your origin.

Example

Cache-Control: public, max-age=86400
Cache-Control: private, no-store

The first lets any cache keep the file for a day. The second keeps personal data out of caches entirely.

Common mistakes

• Believing no-cache means do not store; it means revalidate before reuse. no-store forbids storing.
• Giving HTML a year-long lifetime without versioned URLs.
• Letting a CDN cache logged-in pages by omitting private.

Related

• Browser cache
• CDN
• TTL
• Guide: Cloudflare cache rules
• Tool: Http header checker

This page is general information written by our editorial team and updated when documentation changes. Servers and providers differ, so test changes safely first. See our editorial policy and disclaimer.