Find Bugs Faster With Fiddler

Capture, inspect, and modify HTTP traffic so you can find bugs in minutes, not hours, even when logs conflict across systems.

20+ years

trusted debugging heritage

4M developers

building and debugging with Fiddler

4.4/5 rating

overall G2 user rating

Fiddler Tools

Choose Your Fiddler Tool

Fiddler Everywhere is the recommended, supported tool for professional cross-platform debugging. Fiddler Classic is the legacy Windows-only debugging tool for individual, non-commercial use only. FiddlerCore embeds traffic capture into your own .NET applications.

recommended

Fiddler Everywhere

The modern Fiddler tool for professional developers and teams debugging HTTP traffic across Windows, macOS, and Linux.

Windows · macOS · Linux · Free Trial

Starts at $7 / month

Capture, inspect and modify HTTP traffic, including HTTP/2.
Create, test, and replay requests HTTP/1.1 and HTTP/2 requests.
Debug faster with agent-assisted traffic analysis using Fiddler MCP.

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Start Free Trial

Windows-only tool for personal use

Fiddler Classic

For non-commercial users debugging on Windows.

Windows Only · For Personal Use Only

Free

Manually inspect and debug Windows HTTP/S traffic.
Basic Composer support for quick API calls and request edits.
Legacy tool in maintenance mode with community support.

Compare with Fiddler Everywhere Download Fiddler Classic

Embeddable .NET traffic capture library

Fiddler Core

For organizations embedding traffic capture into their own .NET applications, products, or internal systems.

.NET

Custom pricing

Embed traffic capture directly into your app.
Build custom monitoring, diagnostics, and internal tooling.

Try For Free

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How to Start Your Fiddler Journey

1 Try the Fiddler product(s) and the web debugger that aligns with your needs.

2 Integrate Fiddler into your workflow for rapid, elegant debugging and troubleshooting.

3 You’ll start realizing the high value of benefits of Fiddler through the acceleration of both your time and cost savings.

Hundreds of Thousands of Organizations
are Using Fiddler

Join these companies and the 4 million developers who are already building, running, and debugging with Fiddler proxy tools.

4.4 Out of 5 Overall User Rating

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.

Support & Learning

Blog

How to Select the Right Fiddler Tool for You

Resource

Fiddler Everywhere – Licensing and Purchasing FAQs

Resource

Fiddler Everywhere - Getting Started

How Can We Help? We'd Love to Hear from You!

Glossary

Network Debugging
Network debugging is the process of identifying and resolving issues in web applications by inspecting and modifying HTTP/S traffic between a client, usually a web browser, and a server. It involves using tools to intercept, analyze, and manipulate web requests and responses, allowing developers to troubleshoot problems, optimize performance, and ensure security and functionality. Common tasks in web debugging include examining network traffic, checking for errors in code, and testing how the application behaves under different conditions. Fiddler Everywhere is a powerful web debugging proxy to facilitate your debugging efforts and optimize your processes.
Network Capturing
The process of intercepting, recording, and analyzing data packets as they travel across a network, allowing developers and QA professionals to monitor the communication between devices, identify issues, diagnose problems, and ensure the security and performance of networked applications.

Bug
An error, flaw, or fault in a software program that causes it to produce incorrect or unexpected results or behave unexpectedly. 
Logging
The process of recording detailed information about the application's execution, often used to track events, errors, and data flow, which helps in identifying issues during debugging.

Breakpoint
A marker set in the code where the execution will pause, allowing developers to inspect the state of the application at that specific point. 
HTTP/HTTPS
The main protocols for web communication, where HTTP (Hypertext Transfer Protocol) and HTTPS (HTTP Secure) are used to send and receive data between a client and a server.

Request/Response
The basic communication model in web debugging, where a client sends a request to the server, and the server returns a response. Analyzing these helps identifying issues. 
Cookies
Small pieces of data used to track user activity that the web server generates and sends to a web browser, which stores the cookies for a predetermined period of time. Debugging often involves inspecting cookies to ensure they are set, sent, and received correctly.

A Trial of Any of the Fiddler Products Gives You:

A fully functional version of the software.
Strict data privacy protection. Your data remains with you, it will never be shared.
Easy upgrade path to a licensed product.
Full access to all online documentation, community forums and tutorials.