HTTP Header Injector — Modify Request & Response Headers

Header Injector adds, modifies, and removes HTTP request AND response headers on the pages your browser loads. Each header is a rule: name it, give it a value, choose what to do, and toggle it on or off. Rules apply at the browser's network layer, so they cover every request — page loads, fetch/XHR, images, even websockets. Each rule can: • set, append, or remove the header • apply to the outgoing request or the incoming response • be scoped by URL (wildcards or regex), HTTP method, and resource type • carry a description — a note to yourself about what it's for Features • Request and response header modification • set / append / remove operations • Wildcard or regex URL matching, plus method and resource-type conditions • Profiles — group rules into named sets (dev, staging, prod) and switch between them with one dropdown • Paste a headers block or a curl command to build rules instantly • Import and export your whole configuration as JSON • A master switch to bypass everything at once • A toolbar badge showing how many rules are active • A debug panel showing which rules matched on the current tab • Settings sync across your devices via your Chrome profile Built on Manifest V3 and the declarativeNetRequest API, so headers are applied by the browser's network layer — no request interception, no page scripts, and no data collection. Your configuration stays in your browser. Open source — the full code is on GitHub, so you can verify exactly what it does: https://github.com/slastrina/http-header-injector More software at https://iokig.com