Implementing a chess AI

Hello community!

Since I didn't know exactly in which category this topic belonged, I am just going to leave it here.

As part of a school project, I am working on implementing a small chess server. A (necessary) part of this project would also be to program an AI so that players can play against the computer whilst waiting for opponents.

As a long-time user of chess.com, my first thoughts of course went to this amazing website :)

I did some research on the internet to see whether open source codes for AI chess players already existed, but didn't find anything.

If anyone could help me with where to begin, or provide me with some links to tutorials, that would be very helpful. Incidentally, how was the AI on this webiste designed? Did you use open source code or did you implement it from scratch?

Any help would be welcome :)

Thanks!

Mat