CJam is a stack-based programming language inspired by GolfScript. It was created by aditsu in 2014. The official interpreter is written in Java.
Consult the CJam cheat sheet (PDF) by User:Lynn.
CJam is Turing-complete. To show this, writing a Brainfuck interpreter wouldn't be too hard. A lazier proof is to say that the Underload commands
:()^ correspond to the CJam commands