HeaderCraft Dev - HTTP Header & Request Modifier

Free, local-first MV3 header modifier with auto-disable timers, environment badge, response delay simulation, and rule hit counters.

┃ HeaderCraft is a 100% free, local-first developer tool built for modern web engineering. ┃ Effortlessly modify HTTP request/response headers, redirect URLs, manipulate query ┃ parameters, and mock API responses directly inside Chrome. Designed from the ground up on Chrome’s secure Manifest V3 engine (declarativeNetRequest), HeaderCraft provides a powerful, high-performance toolkit for developers, DevOps, and QA engineers without subscription paywalls, data collection, or telemetry. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 🛡️ 𝗪𝗛𝗬 𝗖𝗛𝗢𝗢𝗦𝗘 𝗛𝗘𝗔𝗗𝗘𝗥𝗖𝗥𝗔𝗙𝗧? ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ✔ 𝟭𝟬𝟬% 𝗟𝗼𝗰𝗮𝗹 & 𝗣𝗿𝗶𝘃𝗮𝘁𝗲: Your headers, API tokens, and mock data never leave your browser. Zero tracking, zero telemetry, zero external servers. ✔ 𝗧𝗿𝘂𝗹𝘆 𝗙𝗿𝗲𝗲 & 𝗨𝗻𝗹𝗶𝗺𝗶𝘁𝗲𝗱: Unlimited profiles, rules, and mocks. No account required, no subscription tiers, no paywalls. ✔ 𝗦𝗲𝗮𝗺𝗹𝗲𝘀𝘀 𝗠𝗶𝗴𝗿𝗮𝘁𝗶𝗼𝗻: Built-in JSON importer allows you to migrate your existing profiles from legacy tools like ModHeader or Requestly in seconds. ✔ 𝗠𝗮𝗻𝗶𝗳𝗲𝘀𝘁 𝗩𝟯 𝗡𝗮𝘁𝗶𝘃𝗲: Built on Chrome's ultra-fast declarativeNetRequest API for instantaneous execution without slowing down your browser. ✔ 𝗜𝘀𝗼𝗹𝗮𝘁𝗲𝗱 𝗧𝗮𝗯 𝗦𝗰𝗼𝗽𝗶𝗻𝗴: Restrict rules to a single browser tab without affecting your other open tabs or personal browsing sessions. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 🚀 𝗖𝗢𝗥𝗘 𝗙𝗘𝗔𝗧𝗨𝗥𝗘𝗦 𝗕𝗥𝗘𝗔𝗞𝗗𝗢𝗪𝗡 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 𝟭. 𝗖𝗨𝗦𝗧𝗢𝗠 𝗛𝗧𝗧𝗣 𝗥𝗘𝗤𝗨𝗘𝗦𝗧 & 𝗥𝗘𝗦𝗣𝗢𝗡𝗦𝗘 𝗛𝗘𝗔𝗗𝗘𝗥𝗦 ➤ Modify headers on the fly: Set, Append, or Remove any request or response header. ➤ Bypass CORS instantly (Access-Control-Allow-Origin: *, Access-Control-Allow-Methods). ➤ Inject Authorization: Bearer <token> or custom headers for staging and production testing. ➤ Inject Dynamic Variables: Use built-in dynamic tokens ({{$uuid}}, {{$timestamp}}, {{$isodate}}) or custom key-value variables to substitute values across headers. ➤ Expand to Full Tab: One-click pop-out to a full responsive browser tab with optimized spacious viewports for multi-monitor workflows. 𝟮. 𝗨𝗥𝗟 𝗥𝗘𝗗𝗜𝗥𝗘𝗖𝗧𝗦 & 𝗗𝗘𝗩 𝗦𝗘𝗥𝗩𝗘𝗥 𝗥𝗘𝗪𝗥𝗜𝗧𝗜𝗡𝗚 ➤ Map production or staging URLs directly to your local dev server (e.g., redirect https://myapp.com/bundle.js to http://localhost:3000). ➤ Supports resource-type filtering, Exact, Prefix, and RegEx matching. 𝟯. 𝗤𝗨𝗘𝗥𝗬 𝗣𝗔𝗥𝗔𝗠𝗘𝗧𝗘𝗥 𝗥𝗨𝗟𝗘𝗦 ➤ Automatically append, modify, or strip URL parameters (e.g., force ?debug=true or remove utm_source tracking tags). 𝟰. 𝗖𝗟𝗜𝗘𝗡𝗧-𝗦𝗜𝗗𝗘 𝗔𝗣𝗜 𝗠𝗢𝗖𝗞 𝗜𝗡𝗧𝗘𝗥𝗖𝗘𝗣𝗧𝗢𝗥 ➤ Intercept window.fetch and XMLHttpRequest network requests locally without needing a backend server. ➤ Return custom HTTP status codes (200, 400, 401, 500) and mock JSON payloads to test frontend error handling. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 🔐 𝗣𝗘𝗥𝗠𝗜𝗦𝗦𝗜𝗢𝗡𝗦 & 𝗣𝗥𝗜𝗩𝗔𝗖𝗬 𝗧𝗥𝗔𝗡𝗦𝗣𝗔𝗥𝗘𝗡𝗖𝗬 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ HeaderCraft requires only minimal permissions strictly necessary for network rule execution: ✦ declarativeNetRequest: Used natively to modify HTTP headers and perform URL redirects locally. ✦ storage: Used to persist your custom profiles locally in your browser. ✦ alarms: Used for background alarms and dynamic variable updates. [ 𝗛𝗲𝗮𝗱𝗲𝗿𝗖𝗿𝗮𝗳𝘁 𝗱𝗼𝗲𝘀 𝗻𝗼𝘁 𝗰𝗼𝗹𝗹𝗲𝗰𝘁, 𝘀𝘁𝗼𝗿𝗲, 𝘁𝗿𝗮𝗻𝘀𝗺𝗶𝘁, 𝗼𝗿 𝗮𝗻𝗮𝗹𝘆𝘇𝗲 𝗮𝗻𝘆 𝘂𝘀𝗲𝗿 𝗱𝗮𝘁𝗮. ]