avwo/whistle

Whistle is a cross-platform network debugging proxy tool built on Node.js, the JavaScript runtime often used for server-side web development. A proxy sits between your browser or app and the internet, letting you intercept and inspect the network traffic flowing through, similar in purpose to tools like Charles or Fiddler, which are listed as related references in the project topics. It supports HTTP, HTTPS, HTTP/2, WebSocket, and TCP traffic, allowing developers to capture and modify requests and responses as they happen. This is useful when you want to understand what data your app is sending and receiving, or when you need to simulate different server responses for testing. Whistle also supports several proxy modes including HTTP, HTTPS, Socks, and reverse proxy. The tool runs on macOS, Windows, and Linux including headless server environments. You install it globally via npm (Node's package manager) with a single command, start it with a simple command-line instruction, and configure your system or browser to route traffic through it. A built-in web interface lets you manage traffic captures, rules, and plugins from one place. The plugin system lets you extend its functionality or use it as an npm module inside other Node.js projects. A desktop client is also available for those who prefer to skip manual configuration steps.