Header Override

An easy-to-use, lightweight browser extension to modify headers with local, URL-based rules.

Get the extension
Local rulesNo trackingManifest V3

Built for debugging

One small tool for request header changes.

Header Override keeps the workflow deliberately narrow: add a rule, choose the header, scope it to a URL pattern, and let the extension apply it. It is built for the moments when you need to modify headers quickly without changing application code.

Set request headers

Add or replace request headers from the extension popup.

Target URL patterns

Scope rules with browser-supported URL filter patterns.

Keep rules tidy

Enable, disable, delete, and annotate rules with comments.

Stay local

Rules are saved locally in your browser and never sent to a server.

Screenshots

See the extension where the work happens.

Header Override promo tile showing the extension icon and browser header rule workflow

Promo tile

Example rule

A fast way to test one request path.

Header Override
OnHeaderValueURLComment
X-Debug-Modetrue|https://api.example.com/*Staging API checks

Common uses

When a header would answer the question faster.

  1. Send debug headers to staging APIs without touching application code.
  2. Reproduce customer-specific request behavior with a scoped URL filter.
  3. Toggle backend flags while testing UI flows in your browser.
  4. Document temporary QA rules before removing them.

FAQ

Answers for searchers and reviewers.

What is Header Override used for?

Header Override helps developers, QA teams, and support engineers modify HTTP request headers from the browser for scoped debugging and testing workflows.

Are header rules sent to a server?

No. Header rules are stored locally in browser extension storage and are used only to apply the request header changes you configure.

Can rules target specific URLs?

Yes. Each rule can be scoped with browser-supported URL filter patterns, so header changes apply only to the requests you choose.

Local by design

No analytics. No tracking. No external servers.

Rules are saved in your browser's local extension storage and used only to apply the header changes you configure. Header Override does not transmit your rules, browsing activity, or website content to the developer or third parties.