Caching

Cache-Control

Set freshness and storage rules with max-age, public, private, no-cache, no-store, and immutable response directives.

9 minute lesson

~~~

Cache-Control contains directives for caches.

Cache-Control: public, max-age=3600

This response can be stored by shared caches and remains fresh for one hour.

Useful directives include:

  • private: only a private cache should store it.
  • no-store: do not store the response.
  • no-cache: storage is allowed, but validate before reuse.
  • max-age=60: fresh for 60 seconds.
  • immutable: the URL’s content will not change while fresh.

no-cache is often misunderstood. It does not prohibit caching. It requires a check before reuse.

Versioned assets such as /app.a1b2.css can use a long lifetime and immutable. When the file changes, its URL changes too. Personalized account pages usually need private or no-store.

Lesson completed