Charles vs Mediator

Charles is a web proxy and HTTP monitor for developers who need to inspect traffic from browsers and other internet applications configured to use it. While recording is enabled, it captures and displays HTTP and SSL/HTTPS requests and responses, including headers, cookies, and caching information. SSL Proxying lets users examine HTTPS session contents. They can repeat or edit requests, intercept requests or responses with breakpoints, replay traffic, mock responses, inspect WebSockets, and chain proxies. Bandwidth throttling and added latency simulate slower connections. Charles presents JSON, JSON-RPC, and SOAP in a simplified tree format and supports Flash Remoting AMF0 and AMF3. Its iOS app captures HTTP and HTTPS traffic and can share requests or sessions with desktop Charles. Captured data is stored on the user's computer; Charles says its developers cannot access it. The software runs on iOS, Linux, macOS, and Windows. There is no free plan; a 30-day trial is available. Individual licenses start at $30, paid once for 10+ users, while 1–4 licenses cost $50 as a one-time purchase.

Mediator is a free, open-source desktop proxy for debugging gRPC traffic on Linux, macOS and Windows. It can redirect requests to beta or test servers without changes to client code. When an API schema is available, it parses gRPC requests and responses and presents binary messages as a JSON tree. Schemas can come from server reflection, proto source roots compiled with protoc, or FileDescriptorSet files. Matching server rules also allow gRPC and HTTPS decoding after the client installs the root certificate generated by that Mediator installation. Certificates are available in DER and PEM formats, and another installation requires its own certificate. The proxy listens on port 8888 by default. Downloads include Windows MSI, macOS DMG, Apple Silicon macOS DMG and Linux deb packages. Setup examples cover Java, Objective-C/iOS and Go clients. The repository identifies Apache-2.0 as its license.