Header Modifier Pro

Fast, lightweight HTTP header editor. Supports POST, Fetch, and XHR.

Why Header Modifier Pro? Most free header modifiers on the store secretly track your browsing data or require expensive monthly subscriptions. Header Modifier Pro is different: 100% Privacy: Zero telemetry, no analytics, no data harvesting. Your API keys and headers never leave your browser. Pay Once, Own Forever: No recurring subscriptions. A single one-time payment unlocks the tool for life. Header Modifier Pro is the ultimate lightweight developer utility for intercepting and modifying HTTP traffic directly in your browser. Built specifically for modern web development, it seamlessly handles standard requests alongside modern fetch and XHR traffic, allowing you to debug APIs, test authentication, and resolve cross-origin issues without touching your backend code. Core Features: Modify Any Header: Add, edit, or remove HTTP request and response headers in real-time. Modern Traffic Support: Fully compatible with standard page loads, REST API calls, POST requests, fetch, and XHR. CORS Bypass: Instantly strip or append Access-Control-Allow-Origin headers to bypass restrictive CORS errors during local development. Auth Token Injection: Easily append Authorization: Bearer <token> headers to all outgoing requests to test protected API routes. One-Click Toggles: Enable or disable specific header rules instantly with a clean, developer-focused UI. Zero Bloat: Built on Manifest V3 using the modern declarativeNetRequest API for blazing-fast, secure execution with zero background lag. Whether you are debugging a complex REST API, managing authentication flows, or just trying to get a local frontend to talk to a remote backend, Header Modifier Pro provides a frictionless, native experience to get the job done.