FlowCraft

FlowCraft is a 100% free, open-source Chrome extension that lets you intercept, modify, and mock HTTP requests and responses. Built for developers who value privacy, simplicity, and power. 🎯 Key Features ✅ Response Mocking - Mock API responses with custom status codes, headers, and bodies ✅ Header Modification - Add, modify, or remove request/response headers ✅ URL Redirection - Redirect URLs based on patterns (exact, wildcard, regex) ✅ Script Injection - Inject JavaScript and CSS into pages ✅ Query Parameter Manipulation - Modify URL parameters on the fly ✅ Request Blocking - Block unwanted requests 🔒 Privacy First • 100% Local - All processing happens on your machine • No Telemetry - Zero tracking, analytics, or data collection • No Cloud Sync - Your rules stay on your device • No External Servers - No network requests to external services • Open Source - Fully auditable code (MIT License) 🚀 Perfect For • Frontend developers testing against mock APIs • Backend developers mocking external services • QA engineers testing edge cases • Security researchers analyzing requests • Anyone who needs HTTP-level control 📚 Use Cases • Test your app against different API responses without backend changes • Debug CORS issues by adding proper headers • Test error handling with mock 404/500 responses • Speed up development with instant mock responses • Test against different data scenarios • Block tracking scripts and unwanted requests 🛠️ Technical Details • Built with TypeScript, React 18, and Tailwind CSS • Uses Chrome Manifest V3 for maximum compatibility • Comprehensive test coverage (89 tests) • Full E2E and unit test suite • Open source: github.com/imerljak/flow-craft Support: For issues and feature requests, visit our GitHub repository.