SmallDevTools - Handy developer tools with a delightful interface
Google Open Source - All of Googles open source projects under a single umbrella
Opensource Builders - Find open-source alternatives to commercial apps
whatdevsneed - This is whatdevsneed.
Dev Lake - Dev Lake is a free & open source product analyzing & visualizing the data inside your dev tools, bringing the information you care about to one personalized & practical dashboard.
GitHub Student Developer Pack - The best developer tools, free for students.