debugging-proxy

Open-source native macOS HTTP debugging proxy — intercept HTTPS, inspect APIs, mock responses, debug WebSocket & GraphQL. Community-driven. For developers, by developers.

MCP server enabling agents to debug HTTP requests better (using powhttp)

Free, open-source HTTP, HTTPS and WebSocket debugging proxy for Windows and macOS. Rust core + Electron UI. Alternative to Charles, Proxyman and Fiddler.

Free, open-source Fiddler Classic alternative for Windows. Capture, inspect, filter, replay, compose and mock HTTP/HTTPS traffic with TLS decryption, HTTP/2, HTTP/3 and SAZ support.

Cross-platform network inspection desktop app built with Electron, TypeScript and React

Cross-platform HTTP/HTTPS/WebSocket debugging proxy GUI powered by whistle, built with Electron and React.

Debugging proxy made for web developers

Local HTTP/HTTPS debugging proxy that understands LLM API traffic (OpenAI, Anthropic, Gemini, Copilot): token usage, cost, streaming reconstruction. Sessions saved as plain JSON so coding agents can read them.

Scripts to help with debugging apps (especially iOS apps) using OWAZP ZAP

Dev Proxy — independent third-party profile of a public API surface, by API Evangelist. Dev Proxy is a Microsoft command-line tool for simulating, testing, and debugging API interactions during development.

Proxyman — independent third-party profile of a public API surface, by API Evangelist. Proxyman is a modern, native macOS app for HTTP/HTTPS debugging proxy with advanced features for API development and testing.

Whistle — independent third-party profile of a public API surface, by API Evangelist. Whistle is a cross-platform HTTP, HTTPS, HTTP/2, WebSocket, and TCP debugging proxy built on Node.js. It enables developers to inspect, intercept, modify, and replay network traffic through a rule-based configuration system with a built-in web UI.