Open-source Alternative To Fiddler

Telerik Fiddler is a robust web debugging tool that allows users to monitor, manipulate, and replay HTTP/HTTPS traffic. It provides a wide range of features, including performance testing, web session manipulation, and security testing, making it a comprehensive solution for web development and debugging.

On the other hand, Requestly is an open source tool available as both browser extension and desktop app. It allows users to set up rules for modifying URLs, injecting scripts, and redirecting requests. It provides a broad range of functionalities, including the ability to manipulate both request and response data, making it a versatile tool for front-end developers.

Trusted by developers team at


Comparing Requestly vs. Fiddler

Requestly is a light-weight & open-source alternative to Fiddler that is available as both Browser extension & Desktop app.

Modify HTTP Headers & Responses
Replace URL
Desktop App
Browser Extension
Network Inspector
Session Recording
Performance Testing

Effortlessly collaborate

Collaborate with your teammates to speed up debugging experience. Plus, the rules sync across devices so you can easily access all your rules from multiple device

Active Support

We take pride in providing top-notch support to our users and helping them debug web applications faster. In fact, over 20% of our reviews mention our active support team!

No performance impact

Requestly is lightweight and doesn’t slow down your browsing experience. Our efficient implementation ensures no drain on your system's energy and memory.

Our Users Tell a Better Story

Requestly is used by more than 180,000 developers from 4000+ organizations around the world. We take a lot of pride in providing the best support to our users and making them successful by building the best web debugging solution. Our users love us and so will you. 

Michael Levinson

Michael Levinson

CPO & Co-Founder

Requestly not just made it easier for us to develop, test & debug our code on our customer sites but It also helps us do engaging product demos to our prospective clients.

Piers Carrigan

Piers Carrigan

QA Lead

Requestly is a game-changer for us. It started with one person and now the entire team uses Requestly to test our Staging code on production customers & non-customer sites. We more confidently ship product updates now.

Mike Mitchell

Mike Mitchell

QA Engineer at Clayton Homes

I'm a big fan of Requestly, and use it on a daily basis as a QA Engineer. It removes the need to use Charles pretty often, which is always nice. Not that Charles wouldn't do the job, it's just super convenient to not need to open a separate application to do the same things -- instead I can just use Requestly directly in Chrome

Carl Hand

Carl Hand

Senior Software Engineer at Workday

Requestly is awesome. I used to use Charles proxy in my day to day work but it always messed with my wifi. I haven't had any issues with Requestly. Requestly's UI is amazing too and great to work in

Robert Wharton

Robert Wharton

Senior Product Manager at Metrical

Requestly has been a lifesaver for testing our product on our customers websites. Everyone's stage sites are a hot mess of half finished dev projects, but Requestly allows us to mock up stage sites in seconds that better reflect the live sites!

Kos Breton

Kos Breton

Director (Management) at Coinbase

Thank you for making this great addon. I just checked out Requestly and indeed it is very easy to set up. It helps me customize my browsing experience entirely. Keep up the great work!

Pre-built, embeddable components

Web debugger

Lightweight web web debugging proxy to modify HTTPs request & response

modify response editor

Modify API Response

Develop frontend without a backend or Modify existing API responses on production environment

modify headers editor

Modify HTTP headers

Add, delete or override request & response headers

redirect request editor

Redirect API and script requests

Redirect APIs/Scripts from one environment to another (e.g. Prod to Staging)

insert script editor

Insert Custom Scripts

Inject custom scripts/styles on external webpages for testing/demo purposes.

Built by us, designed by you

Open-source & Web-based API Client

A comprehensive and web-based tool for modifying and testing APIs.

network inspector

Import cURL requests

Import your cURL requests easily from other API platforms

host switcher

Send API requests and test responses

You can customize request headers, query parameters, and request body payloads to test different scenarios.

analytics inspector

History of API requests

Find the History of API Requests you made to debug them easily.

Report bugs in seconds

Session Recording

Data rich bug reporting with Network logs, Console logs, Session Video & env details.

minimal configuration for bug reporting

Simple configuration

Simple one-time configuration. Define domains where Requestly should record the browsing sessions in background

automatic recording

Automatic recording

Requestly automatically records sessions on configured domains. No need to manually start/stop recording

share sessions

Share sessions

Found an unexpected behaviour/bug, download or share with your developers in a single click

Frequently Asked Question

What Fiddler is used for?

The tool enables you to inspect incoming and outgoing data to monitor and modify requests and responses before the browser receives them

Is Fiddler free to use?

No, Fiddler has a free trial, after that you have to pay for the product 

Is Fiddler open source?

No, Fiddler is not a open source tool

How much does Fiddler Cost?

Fiddler everywhere cost $10 per month per user

Is Fiddler a proxy server?

Fiddler is a web-debugging proxy that monitors, inspects, edits, and logs all HTTP(S) traffic and issue requests between your computer and the Internet.

Download Requestly
Requestly Debugger Proxy

Ready to get started?

Empowering frontend developers to achieve more in development, testing & debugging workflows.