MockHeader
Star on GitHub Add to Chrome — It's free

Open source · ModHeader alternative

Modify HTTP headers. Stay local.

Permanently free. Rules stay on this device. Nothing is uploaded. Coming from ModHeader? Import the JSON.

Add to Chrome — It's free Star on GitHub

MIT. No account. No telemetry.

MockHeader extension screenshot

How it works

  1. 1

    Install

    Load MockHeader in Chrome. No account. It never talks to a server.

  2. 2

    Edit or import

    Set, append, or remove headers in the popup. Or import a ModHeader JSON export.

  3. 3

    Keep it here

    Profiles live in chrome.storage. Filters limit where rules run. Nothing is uploaded.

What it does

Set, append, or remove a header

Request and response headers from the popup. Chrome applies them through declarativeNetRequest. Nothing is proxied.

Toggle a row or a profile

Turn a rule off for one pass and on for the next. Same page, no app deploy.

Filter URL, tab, window, resource, time

Keep tokens on the traffic you meant to touch.

Redirect with a wildcard or regex

From is a Chrome URL filter. To is the destination, or a regex substitution.

Import ModHeader profiles

Export JSON there, Import here. Conversion stays on this device. Independent project — not affiliated with ModHeader.

Permanently free. Local only.

MIT. No paid plan, no analytics, no backend. Source is public.

Install MockHeader

Permanently free. Open source. Nothing leaves this device.

Add to Chrome — It's free

FAQs

Open the popup. Enter the header name (for example Authorization) and its value, then leave the rule enabled. Matching requests pick it up right away.
Yes. Export JSON from ModHeader, then choose Import in MockHeader. Compatible headers, filters, and redirects convert locally. See From ModHeader.
Yes. Permanently free. No account, no paid plan. MIT licensed. Chrome today; load unpacked from GitHub until the store listing is live.
No. There is no backend. Profiles stay in chrome.storage on this device. Nothing is uploaded. See the Privacy Policy.