OpenType.js
Font creation technologies have so far largely been written in C or Python and offered to users as desktop applications or command line tools. Since 2014, the library OpenType.js has been able to parse and generate fonts in JavaScript. This opens up exciting possibilities for detailed control over all of aspects of typography on the web.
By parsing the binary font format, OpenType.js provides direct access to the letter shapes of each of the glyphs in the font.
Once we have access to the shapes, it's easy to experiment and generate new letter forms.
OpenType.js is used in a number of popular open-source and commercial tools such as p5.js, Prototypo, FontSelf and Metapolator.