Telerik Fiddler

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



Key Features

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.

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.

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.

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.”

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.

Want Telerik Fiddler Power in
Your .NET App?

Progress® Telerik® FiddlerCore Embedded Engine 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 Telerik FiddlerCore

Supported Technologies

Any Browser

Telerik Fiddler web debugging proxy helps you record, inspect and debug traffic from any browser.

Any System

Debug web traffic from any Windows-based PC, Mac or Linux system and mobile devices alike.

Any Platform

Telerik Fiddler is ready to help, no matter what platform or language you use to develop.

Companion Tools

Fiddler and Geoedge

Debug traffic from any geo-location with Geoedge

Leverage Telerik 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


Telerik FiddlerCore

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

More about Telerik FiddlerCore

Telerik FiddlerCap

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

More about Telerik FiddlerCap

Telerik 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
Telerik FiddlerScript Editor

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Support and Learning

Go social
Eric Lawrence

About Eric Lawrence,
Fiddler and Telerik

In 2012, we added Fiddler to the Progress Telerik product family. Even more exciting is that the creator of Fiddler, Eric Lawrence, came over from Microsoft to join the team; greatly enhancing Fiddler over three years.

The Fiddler community is very important to us. We're committed to keeping Fiddler free and expanding its value by further investing in the tool.

Next Steps

Download Telerik Fiddler Get Telerik Fiddler web debugger. It's free.
Ask the community Go to Fiddler forums to get help.
Simulate user load with Telerik Fiddler Test Studio load testing powered by Telerik Fiddler.