The Transistortester is a device for identifying and checking electronic components. It also offers additional functionality like a PWM signal generator for example. And it's OSHW.
This repo is meant to provide a convenient way to download firmware packages, documentation files, PCB files and more.
The project's webpage is https://www.mikrocontroller.net/articles/AVR_Transistortester and the official (and cumbersome) repo is https://www.mikrocontroller.net/svnbrowser/transistortester/.