Overhead — HTTP Header Editor od theconcept technologies

Overhead is the header editor you can actually trust.

Add, modify, or remove HTTP request and response headers while you build and test web apps — and switch whole environments (LIVE, DEV, Staging, …) with a single click. Manage everything right from the toolbar popup: quick inline editing, header-name autocomplete, and one-click templates for the headers you reach for most (Authorization, User-Agent, X-Forwarded-For, CORS, and more).

Built to be trusted

100% local — your rules never leave your device.
No tracking, no analytics, no ads. Ever.
Open source, so anyone can verify it.
Uses Chrome's declarativeNetRequest engine, so the extension can't even read your traffic — it only declares rules the browser applies.
Features

Request & response headers: set, append, or remove.
Environment groups with mutually-exclusive switching (LIVE ↔ DEV).
URL wildcard / regex / resource-type conditions.
Optional per-header display labels.
Import your existing ModHeader setup in one click.
Light & dark, keyboard-friendly, fast.
Free and open source, from theconcept technologies.