What is the difference between no-cache and no-store?

no-cache allows caching but requires revalidation before every use. no-store prevents any cache from storing the response at all.

What does immutable mean in Cache-Control?

immutable tells the browser the response will never change, so it should not revalidate even when the user hits reload. Best for versioned static assets.

What is stale-while-revalidate?

stale-while-revalidate allows serving a stale cached response while fetching a fresh copy in the background. This improves perceived performance.

What is the difference between max-age and s-maxage?

max-age applies to all caches including the browser. s-maxage overrides max-age for shared caches (CDNs and proxies) only.

Cache-Control Header Builder

Visibility

publicAny cache (CDN, proxy, browser) may store the response.

privateOnly the browser may cache — shared caches (CDN/proxy) must not store it.

no-storeNo cache may store any part of the request or response. Strongest opt-out.

Freshness

max-ageHow many seconds the browser may use the cached response before revalidating.

s-maxageOverrides max-age for shared caches (CDN/proxy) only.

Revalidation

no-cacheCache may store, but must revalidate with the origin server before every use.

must-revalidateOnce stale, the cache must not use the response without revalidating.

proxy-revalidateLike must-revalidate but only for shared caches.

immutableResponse will never change — browser should not revalidate even on reload.

Stale

stale-while-revalidateServe stale while fetching a fresh copy in the background.

stale-if-errorServe stale if the origin returns a 5xx error.

Other

no-transformProxies must not modify the response body (e.g. image compression).

Cache-Control Builder

Visibility

Freshness

Revalidation

Stale

Other

Learn More About Caching