HTTP Header Injector
Free, privacy-focused Chrome extension to add, modify and manage custom HTTP headers on your outgoing requests.
Manifest V3 · Zero dependencies · < 20 KB · 100% local storage
Take full control of your HTTP headers
Every HTTP request sent by your browser includes headers: authentication tokens, content types, caching directives, custom flags... HTTP Header Injector lets you define your own custom headers and inject them into every outgoing request, or selectively target specific domains.
Key features
- › Master On/Off toggle — Enable or disable all injection with a single click. Icon updates in real time.
- › Unlimited custom rules — Up to 100 active rules, each with header name, value, and domain filter.
- › Per-rule toggle — Each rule has its own independent toggle switch.
- › Domain filtering — Target specific domains or apply to all traffic.
- › Real-time updates — Immediate changes, no reload needed.
- › Dark & efficient UI — Dark theme, compact cards, tooltips and visual status indicator.
Use cases
- Web development & debugging (X-Debug-Mode, Cache-Control)
- API testing (Bearer tokens, API keys, Authorization)
- Authentication & session testing (CSRF, tokens)
- A/B testing & Feature Flags (X-Feature-Flag, X-Experiment)
- Content negotiation (Accept-Language, Accept-Encoding)
- Security testing (X-Forwarded-For, X-Real-IP)
- CORS & cross-origin testing (custom Origin header)
- Distributed tracing in microservices (X-Trace-ID, X-Correlation-ID)
Privacy & security
- No data collection — zero analytics, zero telemetry
- 100% local storage via chrome.storage.local
- No external network connections
- Zero third-party dependencies — fully self-contained
- Built on Manifest V3 with the declarativeNetRequest API
- Minimal permissions: storage + declarativeNetRequest
- Minimal, auditable code — 3 files, < 20 KB
Technical specifications
- Platform: Chrome Extension (Manifest V3)
- API: declarativeNetRequest (dynamic rules)
- Storage: chrome.storage.local
- Max rules: 100 active
- Size: < 20 KB
- Compatible: Chrome, Brave, Edge, Vivaldi, Opera
Install HTTP Header Injector »
Free · Open source · By Refficience.com / Thomas SOUDAZ