Charles Proxy

Charles Proxy is a network monitoring tool that records HTTP and HTTPS traffic passing through it, letting the user see the full detail of each request and response, including headers, cookies, and body content. It works by acting as a proxy that other applications, browsers, or mobile devices route their traffic through, so it can capture calls without requiring changes to the target application's code.

Beyond passive capture, it can decrypt SSL/TLS traffic for inspection, throttle the connection to simulate slower or less reliable networks (useful for testing how an app behaves on mobile data), and parse structured formats such as JSON, XML, SOAP, and Flash/AMF for easier reading. It also supports rewriting or repeating requests, which helps reproduce bugs or test edge cases without regenerating traffic from the original application.

The tool targets developers and QA professionals debugging web services, REST APIs, and mobile app backends, rather than general consumers. It runs on Windows, macOS, and Linux, so the same setup can be used across a mixed development environment.

It should not be confused with a VPN or privacy tool: Charles Proxy does not route traffic through an external network to hide a user's location or IP address. Its proxying is local, used purely to inspect and manipulate traffic that already passes through the machine it runs on.