SmallDevTools - Handy developer tools with a delightful interface
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
TextLab - TextLab is the fastest way to format, prettify, transform, hash, encode, and decode your data instantly!
Utilso - All-in-one tools for developers
GitHub Student Developer Pack - The best developer tools, free for students.
DevBox - Everyday utilities for the everyday developer