Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
ufdbGuard - URL filter for the Squid web proxy
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.
Blokk Font - Mock-up font for clients who do not understand latin.
Weer - A HTTP protocol debugger with Chrome DevTools frontend interface
UI Generator - Generate Lorem Ipsum UI for your design task.