HTTP Cache Header Generator — Optimize Browser & CDN Caching
Generate Cache-Control, Vary, and ETag headers for web and API responses. Select a caching strategy (public, private, no-cache, no-store), set browser and CDN TTLs, and configure advanced directives like stale-while-revalidate. Outputs ready-to-use snippets for nginx, Express.js, and Apache.
How to Use HTTP Cache Header Generator — Optimize Browser & CDN Caching
How to Use the HTTP Cache Header Generator:
Choose a Preset: Click a preset card to load a pre-configured caching policy. Available presets include HTML pages (short public cache), versioned assets (immutable for 1 year), CDN with fallback (short browser TTL, long CDN TTL), API response (private, must-revalidate), stale-while-revalidate, and no-cache for sensitive data.
Select a Cacheability Scope: Choose the top-level directive that controls who can cache the response. Public allows CDN and proxy servers to cache it. Private restricts caching to the end-user browser only. No Cache allows caching but requires revalidation before each use. No Store prevents any caching entirely.
Set the Browser TTL (max-age): Click a preset duration button (0s, 1m, 5m, 1h, 1d, 7d, 30d, 1yr) or type a custom value in seconds. The human-readable equivalent is displayed alongside the value.
Set a CDN TTL (s-maxage): Tick the CDN / proxy TTL checkbox to add an s-maxage directive that overrides max-age for shared caches such as CDNs. A CDN TTL longer than the browser TTL (e.g. max-age=300, s-maxage=86400) lets CDNs cache aggressively while keeping browser caches short.
Configure Advanced Directives: Enable immutable for fingerprinted static assets that will never change during their TTL. Use must-revalidate to prevent serving expired entries. Enable stale-while-revalidate with a window (in seconds) to serve stale content while refreshing in background. Enable stale-if-error to serve stale content when the origin returns a 5xx error.
Configure the Vary Header: Select which request headers the response varies by. Accept-Encoding is recommended for all compressed responses. Add Authorization when responses are user-specific. Add Origin for CORS-aware CDN caching.
Set ETag Type: Choose Strong (exact match, default), Weak (W/"…" prefix, approximate match), or None to omit ETags entirely. Immutable assets rarely need ETags since they are fingerprinted.
Copy the Output: The Cache-Control and Vary values are shown as coloured pills for quick reading. Click a tab (HTTP Headers, nginx, Express, Apache) to view the corresponding code snippet and click Copy to copy it.
Common Use Cases:
- Versioned static assets: Use the Versioned assets preset to get Cache-Control: public, max-age=31536000, immutable for fingerprinted JS/CSS/fonts.
- HTML documents: Use HTML pages preset — short max-age with must-revalidate so browsers always serve fresh HTML.
- API endpoints: Use the API response preset — private, max-age=0, must-revalidate prevents shared caches and ensures freshness.
- CDN-fronted APIs: Use CDN with fallback — short browser TTL keeps user data fresh while CDNs cache longer and serve stale during revalidation.
- Sensitive pages: Use No Cache or No Store for login pages, payment forms, and personal dashboards.
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