Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
Mac CLi - OS X command line tools for developers
Weer - A HTTP protocol debugger with Chrome DevTools frontend interface
Phunt - Product Hunt command line interface
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.
GitHub CLI - Official CLI tool for using GitHub from the command-line.