Otterchat is running on a custom imageboard software called nobo which is short for "new otter board".

nobo was developed by me over the course of a year, as a more modern replacement for the Wakaba script that Otterchat was running on previously, with the intention of building in more features and making the whole site easier and more fun to use.

nobo is developed using the Wt library. I'm still doing my best making improvements and fixes, and would much appreciate your feedback to that end.

Even after a year this is still an early version, there are lots of ideas and not so much free time. I'd like to eventually release the source code under GPL license, so please let me know if that is something you would be interested in.