Created by Einar Lielmanis, maintained and evolved by Liam Newman.
All of the source code is completely free and open, available on GitHub under MIT licence, and we have a command-line version, python library and a node package as well.
We use the wonderful CodeMirror syntax highlighting editor, written by Marijn Haverbeke.
Made with a great help of many contributors. Special thanks to:
Jason Diamond, Patrick Hof, Nochum Sossonko, Andreas Schneider, Dave Vasilevsky, Vital Batmanov, Ron Baldwin, Gabriel Harrison, Chris J. Shull, Mathias Bynens, Vittorio Gambaletta, Stefano Sanfilippo and Daniel Stockman.