Effective date: 2026-07-11
Headmaster is an open-source Chrome extension that adds, overrides, or removes HTTP request headers on URLs matching patterns you define.
Headmaster does not collect, transmit, sell, or share any user data. It has no servers, no analytics, and makes no network requests of its own.
The only data Headmaster keeps is the rules you create — the header names,
header values, URL-filter patterns, labels, and enabled/disabled state you enter
in the popup. These are stored locally on your device using Chrome’s
storage.local API. They never leave your machine and are visible only to you.
If you use Export, a JSON file of your rules is written to your computer by your own action. Headmaster does not upload it anywhere.
To be explicit, using Chrome Web Store’s categories, Headmaster does not collect or transmit any of the following:
declarativeNetRequestWithHostAccess — lets Chrome apply your header rules
through its declarative rules engine. This API modifies headers without the
extension ever reading your requests or responses.storage — saves your rules locally so they persist between sessions.activeTab — when you open the popup, Headmaster reads the current tab’s
URL to show how many of your rules apply to that page. It is used only for that
count and is never stored or transmitted.optional_host_permissions) — requested per site, at
runtime, only when you add or enable a rule for that site. Headmaster can
only modify headers on hosts you have explicitly granted.If this policy changes, the effective date above will be updated and the change
recorded in the project’s CHANGELOG.md.
Questions or concerns: mattmorganpdx@gmail.com, or open an issue at https://github.com/mattmorganpdx/headmaster.