This predates the Internet so maybe I’m in the wrong category, but I just stumbled across what must be the first online go server, and I thought I’d write about it here since there doesn’t seem to be any information about it anywhere else:
This was apparently written by Mark Pavicic and “Herman 
” way back in 1976 on PLATO, a time-sharing system that allowed multiple users to run games, educational, and communication software on a single mainframe computer. I remember using PLATO a few times in elementary school and have been reading about its history, so today I thought I would try logging into an emulator:
After I got online there and went to BigJump with the full list of available programs, I discovered 0playgo on the 3rd or 4th page. There’s a simple interface for setting up a pre-arranged match with another player on the system - up to 10 “channels” of custom games are available. After the game starts, you play moves by entering coordinates:
At the end of the game you can type pass but it doesn’t appear that there’s any scoring system. There’s also a bot you can play against, but it mostly just plays random moves (“except for captures”). There is no undo feature, score estimator, rating system, or even player accounts.
There a color version for modern PLATO terminals (I’m not sure when if ever these actually existed):
Also I found a sort of easter egg on the main PLATO system. If you try to get to “go” like this:
