Open-source alternatives to Fiddler

Interactive TLS intercepting HTTP proxy for testing — An interactive TLS-capable intercepting HTTP proxy for penetration testers and software developers.

↔ alternative to Burp Suite、Charles Proxy、Fiddler

gRPC traffic intercept and debugging tools — A suite of gRPC debugging tools. Like Fiddler/Charles but for gRPC.

↔ alternative to Charles Proxy、Fiddler

WebSocket traffic control and proxy — Complete WebSocket Traffic Control with advanced proxy, simulation, and blocking capabilities

↔ alternative to Charles Proxy、Fiddler、Proxyman