An open source, auditable tool to modify HTTP request and response headers. A clean-by-design alternative to ModHeader, with no tracking, no telemetry, and no header hoarding.
Install from the Chrome Web Store →
Header tools need broad access to your traffic, which makes them a high-value supply-chain target. Open ModHeader is built to be safe by design:
declarativeNetRequestonly. The browser applies your rules; the extension never reads your traffic.- No network calls. Zero outbound requests, no analytics endpoints.
- No header history. Nothing is stored except your own rules.
- Minimal permissions:
declarativeNetRequestandstorage.
- Modify request and response headers (set or remove)
- Multiple profiles: switch, rename, duplicate, delete, and drag to reorder
- Tabbed request/response view with per-row, per-section, and global toggles
- Import and export profiles, compatible with ModHeader
- Light and dark themes that follow your system
- Open the extension popup and add a header with Add request header or Add response header.
- Enter the header name and value. Use the Set / Remove control to either set a value or strip the header.
- Toggle individual rows, a whole section, or everything with the Global switch.
- Group related headers into profiles and switch between them. Only the active profile is applied.
Profiles can be copied to the clipboard and pasted into ModHeader (or another Open ModHeader install) via Copy and Import.
Open ModHeader exists because a trusted header extension can quietly turn into a liability. In 2026, a popular header tool was pulled from the Chrome Web Store after a hidden data-collection SDK was found in a signed release. This project takes the opposite stance: minimal permissions, no network access, and source you can audit end to end.
pnpm install
pnpm dev # run in Chrome
pnpm build # production build
pnpm compile # typecheckBuilt with WXT and React. Chrome (Manifest V3) is the current target.
Releases are fully automated with
semantic-release. Every push to main
runs the release workflow, which inspects the
commit messages since the last release and decides what to publish.
Versioning follows Conventional Commits:
| Commit type | Release |
|---|---|
fix: |
Patch (1.0.1) |
feat: |
Minor (1.1.0) |
feat!: / fix!: / BREAKING CHANGE: |
Major (2.0.0) |
docs: chore: ci: refactor: test: |
No release |
When a releasable commit lands on main, the workflow bumps the version,
updates CHANGELOG.md, tags the release, and publishes a GitHub Release with the
built Chrome zip attached. If no commit warrants a release, the workflow succeeds
without publishing anything.
Commit messages are linted locally via a Husky commit-msg hook, so
non-conforming messages are rejected before they reach main. See
CONTRIBUTING.md for details.