mitmproxy : mitmproxy is your swiss-army knife for debugging, testing, privacy measurements, and penetration testing. It can be used to intercept, inspect, modify...
httpbin.org : A simple HTTP Request & Response Service.
httpbin : Testing an HTTP Library can become difficult sometimes. PostBin.org is fantastic for testing POST requests, but not much else. This exists to cover al...
Siege : Siege is an http load testing and benchmarking utility. It was designed to let web developers measure their code under duress, to see how it will stan...
Mockbin : Mockbin allows you to generate custom endpoints to test, mock, and track HTTP requests & responses between libraries, sockets and APIs.
toxy is a fully programmatic and hackable HTTP proxy to simulate server failure scenarios and unexpected network conditions, built for node.js/io.js.