UI Garage - Specific mobile and web design patterns for your inspiration
Fiddler - Fiddler is a debugging program for websites.
UI Movement - The best UI design inspiration, daily
Proxyman.io - Proxyman is a high-performance macOS app, which enables developers to view HTTP/HTTPS requests from apps and domains.
Httpster - A curated showcase of shit-hot web designs.
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.