GitHub

It’s every developer’s worst nightmare—you’re working on a new project feature and you screw up. Enter version control systems (VCS)–and more specifically, GitHub.

By rolling out your project with the service, you can view any changes you’ve made or even go back to your previous state (making pesky mistakes a thing of the past). 

The repository hosting service also boasts a rich open-source development community (making collaboration between teams as easy as pie), as well as providing several other components such as bug tracking, feature requests, task management, and wikis for every project.