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.

Is my data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your input never leaves your device and nothing is logged or stored on our servers.

Does it work offline and on mobile?

Yes. Once the page has loaded it keeps working without a network connection, and the layout is responsive so it stays usable on phones and tablets.

HTTP Cache Header Planner

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

Support

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

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

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Frequently asked questions

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