Fiddler The free web debugging proxy for any browser, system or platform

Web Debugging

Debug traffic from PC, Mac or Linux systems and mobile devices. Ensure the proper cookies, headers and cache directives are transferred between the client and server. Supports any framework, including .NET, Java, Ruby, etc.

Performance Testing

Fiddler lets you see the “total page weight,” HTTP caching and compression at a glance. Isolate performance bottlenecks with rules like “Flag any uncompressed responses larger than 25kb.”

HTTP/HTTPS Traffic Recording

Fiddler is a free web debugging proxy which logs all HTTP(s) traffic between your computer and the Internet. Use it to debug traffic from virtually any application that supports a proxy like IE, Chrome, Safari, Firefox, Opera and more.

Web Session Manipulation

Easily manipulate and edit web sessions. All you need to do is set a breakpoint to pause the processing of the session and permit alteration of the request/response. You can also compose your own HTTP requests to run through Fiddler.

Security Testing

Use Fiddler for security testing your web applications -- decrypt HTTPS traffic, and display and modify requests using a man-in-the-middle decryption technique. Configure Fiddler to decrypt all traffic, or only specific sessions.

Customizing Fiddler

Benefit from a rich extensibility model, ranging from simple FiddlerScript to powerful Extensions which can be developed using any .NET language.
See full list of ready-made add-ons.

 

 

Companion Tools

Debug traffic from any geo-location with Geoedge

Leverage Fiddler and the Geoedge global proxy network to monitor, inspect and debug traffic from over 130 locations. You can access Geoedge’s servers directly within the familiar Fiddler environment and easily switch from one location to another. With Geoedge you get access to:

• High-performance servers - Fast, unmasked and secure access to web content
• True geo-located IPs - Servers physically located all over the world
• Unmatched reliability - 99.9% network uptime

More about Geoedge global proxy network

FiddlerCore

Integrate FiddlerCore into your application. FiddlerCore is the core proxy engine used by Fiddler to intercept and modify web traffic. You can integrate FiddlerCore into your .NET applications to provide unprecedented functionality.

More about FiddlerCore

FiddlerCap

Need to collect a web capture from an end-user and nervous about pointing them at the full version of Fiddler? Try FiddlerCap, a simple "VCR-like" recorder that generates SAZ captures you can open in Fiddler.

More about FiddlerCap

FiddlerScript Editor

The FiddlerScript Editor is a text editor that helps you edit script rules for Fiddler. It offers syntax highlighting and a class explorer to help you author scripts.

More about
FiddlerScript Editor

Check out the Fiddler add-ons

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