Fiddler: The Web Debugging Proxy Tool Loved by Users

Log all HTTP(S) traffic between your computer and the Internet. Inspect traffic, set breakpoints and fiddle with request/response.

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.

Why Use Fiddler?

Key Features

Web Debugging

Debug traffic from PC, Mac or Linux systems and iOS and Android 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.

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

Debug issues in customer environments by recording https traffic with a lightweight companion tool “Fiddler Cap”. Small footprint ideal to quickly record and share web traffic in customer and production environments.

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.

API Development and Debugging

Use Fiddler Composer to quickly test APIs by creating and sending requests. Useful while developing new APIs or when testing existing APIs. Composer is fully integrated with Sessions list; simply drag any session onto composer and edit and test the request.

HTTP/HTTPS Traffic Inspection & Analysis

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

Request & Response Mocking

Mock or modify request and responses on any website. It’s a quick and easy way to change the request and responses to test websites without changes in the code.


Additional Fiddler Tools

There’s a Fiddler for Just About Every Need

Fiddler Everywhere

ALL NEW Fiddler built from ground up to work on all major platforms like Windows, Linux and Mac.

Learn More


The power of Fiddler in your app. A .NET library that allows you to capture and modify HTTP and HTTPS traffic.

Learn More

Fiddler Cap

A lightweight companion tool to capture web traffic from end-users or from customer environments.

Learn More

There’s a Reason Why We’re the
No. 1 Choice for so Many Developers

7.9/10 Ease of Use
7.9/10 Quality of Support
8.6/10 Ease of Setup
Background-G2UserReviews User Reviews

Fiddler is used by tens of thousands of Users daily and they love it! Don’t just take our word for it. G2 Users have consistently rated Fiddler 4.4 out of 5 stars. G2 is a renowned peer-to-peer review site that aggregates user reviews for business software.
Users of provide unbiased user reviews after they objectively access business software.

Read More Reviews on

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Explore Fiddler Everywhere

ALL NEW Fiddler built from ground up to work on all major platforms like Windows, Linux and Mac.