Telerik Fiddler

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

Key Features

Customizable Free Tool

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.

Web Session Manipulation

Edit web sessions easily:just set a breakpoint to pause the processing of the session and permit alteration of the request/response. Compose your own HTTP requests and run them through Fiddler.

Performance Testing

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

Security Testing

Decrypt HTTPS traffic and display and modify web application requests using a man-in-the-middle decryption technique. Configure Fiddler to decrypt all traffic, or only specific sessions.

HTTP/HTTPS Traffic Recording

Use Fiddler to log all HTTP(S) traffic between your computer and the Internet. Debug traffic from virtually any application that supports a proxy (IE, Chrome, Safari, Firefox, Opera and more).

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

Want More Telerik Power in Your .NET or JavaScript/jQuery App?

Telerik Fiddler is part of a family of developer productivity tools for .NET and JavaScript ninjas. Make your next project your best yet!

DevCraft: Build Exceptional UI Across Platforms

Whether you are a .NET or a JavaScript developer, Telerik UI controls will help you build outstanding UI twice as fast. Our toolbox covers a wide range of technologies from ASP.NET Web Forms, MVC and Core, to Xamarin and UWP, to Angular, Vue and React—all available in one swift bundle, DevCraft.

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Telerik FiddlerCore: Make Fiddler Your Own

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—now supporting .NET Standard 2.0.

Learn more

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

Use Telerik Fiddler with any platform and language. Now supporting .NET Standard 2.0.

Companion Tools

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.