Charles

Charles is a web proxy that runs on your own computer, recording and displaying all data sent between your browser or client application and remote servers. It allows inspection of SSL traffic in plain text, bandwidth throttling, request repetition, and request editing for technical debugging and backend testing.

★★★★★

5.0(1 ratings)

• Full HTTP proxy recording. Charles acts as an intermediary between client and server, capturing every request and response. All HTTP and HTTPS traffic is logged for detailed real-time analysis.
• SSL plain text visualization. Inspects encrypted connections by installing a root certificate. Displays SSL requests and responses in decrypted form within the interface for debugging secure traffic.
• Bandwidth throttling and latency simulation. Provides the ability to limit transfer speed and add artificial latency to test application behavior under slow or unstable network conditions.
• AJAX and structured data debugging. Views XML, JSON, and AMF (Flash Remoting) requests and responses. Presents data in a tree structure to facilitate analysis of nested content.
• Request repetition. Allows re‑sending a previously captured request to the server multiple times. Used to verify backend changes or reproduce errors.
• Request editing for testing. Modifies parameters, headers, or body of a request before sending it to the server. Tests different inputs without altering the original client.
• Breakpoints for interception. Intercepts and halts a request or response to modify it manually. Injects data or forces error codes during debugging sessions.
• W3C validation of HTML, CSS, and RSS. Automatically sends captured HTML, CSS, or RSS responses to the official W3C validator and displays markup or style errors.
• Port mapping and request rewriting. Redirects requests to another local or remote server, or replaces parts of a request or response based on defined rules.
• Session recording and export. Saves all captured traffic to a session file (.chls) and exports to XML, JSON, or plain text for external analysis.
• Traffic filtering and search. Filters by domain, MIME type, HTTP method, or response status. Includes a search engine within request and response content.
• WebSockets support. Inspects messages sent and received via the WebSocket protocol, displaying text and binary frames in real time.

Charles was initially developed by Karl von Randow in 2002. The first public version was released for macOS and later extended to Windows and Linux. The main author has maintained the tool as a private commercial project. The program is written primarily in the Java language, enabling cross‑platform operation via the Java Virtual Machine. The company behind the software is Xk72 Limited, based in New Zealand.

Alternatives to Charles:

Fiddler

Fiddler is a web debugging proxy that logs all HTTP(S) traffic between a computer and the internet.

Price: Free   Size: 141 MB   Version: 5.0.20242.10753   OS: Windows