HeaderKits

Simple yet powerful toolkit to modify headers, redirects, blocks, and query params without leaving your tab. HeaderKits is designed for a clear developer workflow. Create profiles, apply templates, and reshape HTTP traffic while you stay on the page you are testing. Ideal for local API work, staging auth headers, redirects to localhost, query cleanup, and temporary client identity headers. Be careful. Do not share exported profiles or environment values with anyone you do not trust. Headers and env placeholders can contain sensitive information such as API tokens. If someone has those values, they may gain access to services you use. WHAT YOU CAN DO • Manage multiple profiles (enable/disable, always-on layers, colors) • Set, append, or remove request and response headers • Redirect or block matching URLs (literal or regex) • Set or remove query parameters • Scope rules by method, domain, URL filter, and resource type • Use templates (auth, content types, User-Agent + Client Hints, CORS, blocks, and more) • Store secrets as env placeholders: {{TOKEN}} or {{env.TOKEN}} • Import and export JSON (into the selected profile, or as new profiles) • Pause all rules without deleting them • Optional activity log for debugging matched rules (off by default) • Compact popup plus a full editor HEADERKITS CAN HELP YOU • Develop and test web apps and APIs • Attach or strip auth headers for local and staging environments • Spoof User-Agent and Client Hints for server-side checks (network request layer) • Clean tracking query params or block noisy third-party requests • Keep control without a paid cloud tool PRIVACY HeaderKits believes in privacy. Your rules and env values stay offline in browser extension storage. No ads. No account. No telemetry. Nothing is uploaded to a HeaderKits server. IMPORTANT LIMITS HeaderKits modifies network requests via declarativeNetRequest. It does not rewrite page JavaScript such as navigator.userAgent. Response body rewriting and custom per-request scripts are out of scope. SUPPORT & SOURCE Feature requests and bug reports: https://github.com/raihanadiarba/headerkits Documentation: https://github.com/raihanadiarba/headerkits/tree/main/docs Privacy policy: https://github.com/raihanadiarba/headerkits/blob/main/docs/privacy.md