Reassembly has a large community of modders, and hundreds of items in the Steam Workshop to alter your game experience. Everything from one-line adjustments to the game, to complete reworks of the galaxy and UI.
Reassembly Web Development Kit (RWDK)
Modding Tutorial by Lapapsnow (mostly using RWDK)
- part #1 – Adding Basic Blocks
- part #2 – Adding Ships and More Block Types
- part #3 – Extra Data Practices
Steam Mod Downloader if you want to use mods from the workshop outside of Steam, this site worked the last time I tried it. Make sure the URL you enter is http://, not https://