If you happened to visit those websites during Fastly's outage, you saw the relatively unhelpful error message below. As a frontend developer, my eyes scan error messages like these for numbers - in this case, the "503" - indicating that the error isn't my fault, and I can move on with my life.

With one click: Intercept & view all your HTTP(S) - Mock endpoints or entire servers - Rewrite, redirect, or inject errors

HTTP is fundamental to modern development, from frontend to backend to mobile. But like any widespread mature standard, it's got some funky skeletons in the closet.

script-httpd is essentially a very basic CGI server which forwards all requests to a single script. A design goal is to be as close to zero-config as possible.

localtunnel exposes your localhost to the world for easy testing and sharing! No need to mess with DNS or deploy just to have others test out your changes.

This repo is the server component. If you are just looking for the CLI localtunnel app, see (https://github.com/localtunnel/localtunnel).

A powerful REST API Client with cookie management, environment variables, code generation, and authentication for Mac, Window, and Linux

beeping - HTTP Monitoring via API - Measure the performance of you servers

Interactive cli tool for HTTP inspection

Wuzz command line arguments are similar to cURL's arguments, so it can be used to inspect/modify requests copied from the browser's network inspector with the "copy as cURL" feature.

Chisel is a fast TCP tunnel, transported over HTTP. Single executable including both client and server. Written in Go (Golang). Chisel is mainly useful for passing through firewalls, though it can also be used to provide a secure endpoint into your network. Chisel is very similar to crowbar though achieves much higher performance.

An interactive console program that allows traffic flows to be intercepted, inspected, modified and replayed.

A friend once told me that his university has an HTTP(S)-only proxy, and thus he is unable to SSH to hosts outside. 5 hours of intensive coding later using code borrowed from my course assignment, here’s HOP.

HOP is a tool meant to tunnel any sort of traffic over a standard HTTP channel.

Hulken is a stress testing tool for everything speaking HTTP. Hulken supports multiple urls, GETs and POSTs, static and dynamic payloads, multiple agents and more. Hulken is highly configurable but defaults to some reasonable settings. Hulken works both as a library and a stand-alone command line tool. Hulken is swedish for The Hulk.

http-prompt - HTTPie + prompt_toolkit = an interactive command-line HTTP client featuring autocomplete and syntax highlighting

Galeb is an open source Router as a Service software.