Some general language-wonk sorts of sites:
Github Collections: Programming Languages: As of 1 June 2020, I've collected the top two or three dozen into this site (at least).
Codelani appears to be a comprehensive list of languages (over 4,000); the "patterns" section is more a collection of "language atoms" that make up a lot of language syntax and semantics; I need to create my own ontology around this
Awesome Open Source: Language Projects | Scripting Language Projects | Virtual Machine Projects
Catseye has an interesting collection of tiny languages, many of which are esoteric in nature, but some of which have some interesting principles that are worth investigating. It looks like the author of the site spends a ton of time just writing a new language each month or something, going all the way back to 2008 and earlier.... TODO: Go through the site and categorize each language on this page with comments and thoughts
Build Your Own X: Languages included here as well
Last modified 30 July 2025