FlowCraft

About

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.