Header Master

Real-time HTTP request header manipulation for advanced web testing and proxy simulation. Built by Txyber.

Header Master — Short Store Description Modify outgoing HTTP request headers for web testing, API debugging, and Quality Assurance workflows. Header Master is a Manifest V3 developer extension that lets users create, manage, and apply custom request headers directly in the browser. Configure domain-based rules, use dynamic variables, and control header conflicts with overwrite, append, or bypass modes. Designed for developers, QA teams, backend engineers, staging environments, feature flag testing, localization testing, and request tracing. Features 1.Add, edit, enable, and disable custom headers 2. Apply headers using Manifest V3 network rules 3. Scope rules to selected domains 4. Support dynamic variables 5. Master on/off switch 6. Local-only storage with no external accounts or analytics Permissions declarativeNetRequest — Modify outgoing request headers declarativeNetRequestWithHostAccess — Apply rules to selected websites storage — Save local extension settings and header rules Privacy No accounts required No remote analytics No data sent to external servers All configuration stored locally in the browser