Collab on Code - Write code remotely in real-time with coworkers and clients
Proxyman.io - Proxyman is a high-performance macOS app, which enables developers to view HTTP/HTTPS requests from apps and domains.
Kite - Kite helps you write code faster by bringing the web's programming knowledge into your editor.
httpbin(1) - HTTP request and response service
Slowbug - Debug you code in slow-mo!
HTTP Toolkit - Beautiful, cross-platform & open-source tools to debug, test & build with HTTP(S). One-click setup for browsers, servers, Android, CLI tools, scripts and more.