StSLib is an open-source group of generalized common keywords, mechanics, relic hooks, and power hooks for mod makers to use in order to avoid each mod maker needing to re-implement the same code over and over.

BaseMod is an open-source API for modding Slay the Spire. It provides an extra layer on top of ModTheSpire's low-level API to make the creation of mods easier.

ModTheSpire is the mod loader for Slay the Spire. You must subscribe to ModTheSpire if you want to play with mods.