GitHub for Mac utilizes TwUI, an open-source UI framework developed by Twitter, which is based on Core Animation for Mac and is also used in Twitter for Mac to create fast and animatable UIs with modern APIs. GitHub has contributed numerous improvements and bug fixes to their version of TwUI, including HiDPI support and new features like an updated popover, and these enhancements are now integrated into the original TwUI repository. Collaboration with Twitter aims to further enhance TwUI, ensuring its promising future as both parties work together to make the framework even more robust and efficient.