Intercept & Modify
Request Body in Real Time.

Change the way you test APIs. Check the API responses with different inputs, find edge cases, simulate API errors. 

Override XHR/fetch Requests

Using Requestly Modify Request Body rule, you can override the API requests triggered by XHR/fetch. No need to hardcode APIs in frontend code anymore.

Test error paths in your code

Modify API request body to trigger different error paths in your codebase and test the flows without changing anything on backend. e.g. Simulate Payment Timeout Issue, Item out of stock Issue, etc.

1-Click Sharing

Use-Cases in teams are very similar so Requestly makes it easier to share the rules with each other and collaborate faster.

Trusted by developers at


Application and use cases

Here’s how you can use Requestly’s Modify Response feature in your daily workflow

Static Response

Allows you to intercept and replace the original server response with a predefined fixed JSON or string response

Dynamic response

Gives ability to modify the server response programmatically using JavaScript. Write custom JavaScript code that runs on the intercepted response and manipulate its content.

Fake status code

Enables you to change the HTTP status code of a server response. By modifying the status code, you can simulate different server responses without actually altering the content.

Intercept & Modify HTTP Requests

Boost Your Web Development: Advanced Tools for Seamless Debugging.

More from Requestly

An open-source platform that speeds up your web development cycle 10X faster.

Session Recording

Data rich bug reporting with Network logs, Console logs, Session Video and environment details. Share it with your Engineering team for faster debugging.

Mock API Server

Generate custom API responses without actually having a pre-built API or a backend server. Edit Content-Type, Status Code, Headers, and Response body easily on the Mock Server.

Web-based API Client

A comprehensive and web-based tool for modifying and testing APIs. You can test the Mock APIs you’re creating here to fast track your development lifecycle.

For the developers, by the developers ❤️

From Debug to Deploy: Developers Trust Requestly

Simple UI, Huge Impact Loved the intuitive UI for request body modification. Helped in confirming backend security with my senior engineer, even bested Postman Interceptor in some cases.

Ashish Amar
Associate Software Engineer at Rakuten Symphony

Awesome tool. I use it almost daily for my projects to modify request body, headers, etc. Would recommend it to every frontend developer out there. Thank me later 🙂 (Case Study)

Harsh Vats
Frontend Engineer at PingSafe

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 an amazing tool and great to work in.

Carl Hand
Senior Software Engineer at Workday

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

Michael Levinson
Co-Founder & CPO at Joyned

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 Proxy often, which is always nice. I can just use Requestly directly in Chrome

Mike Mitchell
QA Engineer at URBN

This is by far the best tool for managing request headers! Plus the developers are very active meaning you’ll get help if you’re ever stuck or need help solving a problem. I use it daily and couldn’t be happier.

Jose Browne
Senior Engineer at Reddit

App works as expected! Ran into some small issues while creating the rules but the support team was able to help and overcome those.

José Miguel Dias Fernandes
Development Lead at Vodafone

Requestly is user-friendly, brilliant and easy-to-use. I use it on an daily basis and it makes my work easier. After using other tools like Charles – Requestly is a nice new breath of air that I highly vouch for. Apart from the tool being amazing – the support from the Requestly team is phenomenal with them always going above and beyond for their clients.

Marius Ludick
Solutions Architect II at Amazon

Requestly is an amazing tool to get your development work less hassle. The product itself has evolved so much since day-1 and the company is really serious on helping their customer solves their problems. We had this nice session where they shared Requestly features and we were very impressed on its potential. A truly 5-star worthy.

Natchapol Thongruang
Senior Software Engineer at Agoda