Fiddler is a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP(S) traffic, set breakpoints, and "fiddle" with incoming or outgoing data.

Fiddler is a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP(S) traffic, set breakpoints, and "fiddle" with incoming or outgoing data.

mitmproxy is an SSL-capable man-in-the-middle proxy for HTTP. It provides a console interface that allows traffic flows to be inspected and edited on the fly. It also features mitmdump, a commandline tool that provides a tcpdump-like interface for saving, viewing and...


The Google Chrome Developer Tools provide an integrated environment for debugging, optimizing, and understanding a web application, or website, running in Google Chrome. The developer tools are developed partly through the WebKit open source project, where the tools are called...



HTTP Toolkit is a beautiful, cross-platform & open-source HTTP(S) debugging proxy, analyzer & client, with built-in support for modern tools and automatic interception for clients from Docker to Android to iOS.




Charles is an HTTP proxy / HTTP monitor / Reverse Proxy that enables a developer to view all of the HTTP and SSL / HTTPS traffic between their machine and the Internet. This includes requests, responses and the HTTP headers (which contain the cookies and caching information).

Examine, edit, and debug HTML, CSS, and JavaScript on the desktop and on mobile.

CodeTracer is a user-friendly time-traveling debugger designed to support a wide range of programming languages.




Requestly is a lightweight proxy available as a browser extension & desktop app to intercept & modify network requests. Using Requestly you can Modify Headers, Redirect Url, Mock API response, Delay/Throttle requests, etc.




BrowserStack is the world’s largest cloud platform for software testing, with 20,000+ real Android and iOS devices that allow developers to comprehensively test their websites and apps for functionality, performance, and visual appeal.




Open-source Chrome side panel that turns a browser bug into a complete report — screenshot or recording plus console, network, and action logs — and files it straight to Jira, GitHub, Linear, Notion, GitLab, Asana, ClickUp, or Slack.




AI-native platform for intelligent, automated testing of web, mobile, and enterprise apps at scale with real device, browser, and environment support.




The Web Developer extension adds various web developer tools to a browser. The extension is available for Chrome, Edge, Firefox, and Opera, and will run on any platform that these browsers support including Windows, macOS and Linux.




MultiGlancer is a minimalist and open-source tool I've developed to streamline the web development process. It allows developers to view their site on multiple web sizes simultaneously on a single screen. Born out of necessity while perfecting my landing page for ArcanePad.

Develop responsive web apps 5x faster! A must-have DevTool for all Front-End developers that will make your job easier.

The Zed Attack Proxy (ZAP) is an easy to use integrated penetration testing tool for finding vulnerabilities in web applications.




Network Spy is a cross-platform network proxy and traffic analyzer built with Tauri, Rust, and React. It helps developers intercept, inspect, decrypt, and debug HTTP(S) traffic through a fast and modern desktop interface.



Performs real-time mobile and tablet website debugging, offers 50+ device profiles, supports custom resolutions, and features built-in Dev Tools for simultaneous responsive testing.




Sorry Cypress is an open-source platform that serves as an alternative to the Cypress Cloud



Polypane is a browser built from the ground up to create websites and apps. Polypane is the only browser that lets you develop a website for all viewports and devices at once, and gives you the best overview of them.




Debug, troubleshoot and analyse parallel CI tests in Cloud. A drop-in replacement for Cypress Dashboard. Now supporting Playwright.


Fluxzy Desktop is an HTTP and HTTPS debugging proxy for Windows, macOS, and Linux. If you already use Fiddler, Charles, or Proxyman, you know the drill: capture traffic, inspect requests and responses, tweak them, replay them. Fluxzy does all of that, with support for HTTP/1.



HTTP Debugger captures and decrypts HTTP/HTTPS from any Windows app without proxy setup — HTTP/2, WebSocket, SSE, gRPC and localhost included. Edit and replay requests, modify traffic on the fly, and let an AI assistant read the session over the built-in MCP server.








James is a HTTP Proxy and Monitor that enables developers to view and intercept requests made from the browser. It is an open-source alternative to the popular developer tool Charles.

HttpFox monitors and analyzes all incoming and outgoing HTTP traffic between the browser and the web servers.

