January 10, 2021 Ohm is an open-source parsing toolkit for JavaScript which Alex Warth and I have been working on since 2014. You can use it to parse custom file formats or quickly build parsers, interpreters, and compilers for programming languages. This article is not about Ohm itself, but about the Ohm visualizer, which I designed and built in 2015 while working on Alex’s team at CDG.1 Later, t