What is immutable for?

It tells browsers never to revalidate a fingerprinted asset before it expires.

Should HTML be cached?

Usually with no-cache so users always get the latest deploy.

Does this contact my site?

No, the recommendations are generated locally.

HTTP Cache Header Planner

Plan Cache-Control, ETag and max-age headers for any asset type.

Works Offline

Privacy First

No Login

No API

Preset

Options

no-store (never cache)

Visibility

max-age (seconds)

s-maxage (seconds, optional)

must-revalidate

immutable

Generated header

Cache-Control: public, max-age=31536000, immutable

Can be cached by browsers and shared caches/CDNs. Considered fresh for 31536000 second(s) in browser caches. Marked immutable — clients won't even revalidate on refresh while fresh.

About the HTTP Cache Header Planner

Choose an asset type and freshness strategy to get the right Cache-Control, ETag and Vary headers, with an explanation of how browsers and CDNs will behave.

Examples

Example

hashed static asset

Output

Cache-Control: public, max-age=31536000, immutable

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Frequently asked questions

Version 1.0.0 · Updated 2026-08-09 · Runs entirely in your browser