Fiddler

Fiddler is a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet.

Free Windows

mitmproxy

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...

Free Open Source Mac Windows Linux

Charles

Reverse proxy and HTTP proxy and monitor that displays all HTTP(S) traffic to/from your computer.

Commercial Mac Windows Linux

HTTP Debugger

HTTP Debugger Pro - A Professional HTTP Sniffer and Analyzer for Developers

Commercial Windows

HttpFox

HttpFox monitors and analyzes all incoming and outgoing HTTP traffic between the browser and the web servers. It aims to bring the functionality known from tools like...

• Discontinued
  The project is no longer developed. Last version, 0.8.14.1, released in May 2014, is not compatible with Firefox, but the extension still works on XUL-based Firefox forks like https://alternativeto.net/software/waterfox/ and https://alternativeto.net/software/palemoon/

Free Mac Windows Linux Waterfox Pale Moon