Proxyman.io - Proxyman is a high-performance macOS app, which enables developers to view HTTP/HTTPS requests from apps and domains.
Bootstrap 4 Cheat Sheet - An interactive Bootstrap 4 cheat sheet
RegExr - RegExr.com is an online tool to learn, build, and test Regular Expressions.
Bootstrap Magic - Create your Bootstrap 4.0 themes easily with magic
Regulex - Open-source, regular expression parser and visualizer.
HackerThemes - Bootstrap 4 themes and tools for web developers