Believe it or not, GitHub hasn't had an official mobile app -- a pain when you just want to offer some feedback on a project. That won't be a problem from now on. After months of testing, the Microsoft-owned company has released native GitHub apps for Android and iOS. Both let you manage tasks and pull requests (contributions to open projects) on the move, and you can both dish out and respond to comments.
This unsurprisingly won't let you edit code, and the feature set isn't terribly complicated in the app's current state. You'll likely want to fire up your PC for some tasks. GitHub promises that there's "a lot more to come," though, so don't despair if you like the thought of juggling common coding duties and saving some time at work.