We use them every day at Zed for pair programming, we're rather fond of the features :D

Used it the other day with my teammate to pair on some stuff, and it genuinely felt magic. We went from never having used it, to digging through their code together in about a minute, and have used it a few times since. Really nice UX.

"multiplayer notepad" goes back 15 years at least - https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

it was used back with a popular website which opened a text document and anyone viewing could type, but I can't remember the name. That became a thing in Google Docs, Microsoft Office, Floobits, and lots of self-hosted and cloned sites.

IRC was what was initially called multiplayer notepad.

You may be thinking of Hackpad from 2014, which later was bought by Dropbox and morphed into Dropbox Paper. I guess I was thinking that a multiuser IDE is substantially different than a multiuser text editor. I did notice that Zed is by the same team that brought us tree-sitter, which is a wonderful innovation that many text editors are now using to good effect. I was wondering if were powerful enough for one person to be debugging some code in the same session that another person was refactoring.

Earlier than that; I wanted to say EditPad but that's not it. I found it; EtherPad in 2008 is the one I was thinking of, but the history of collaborative editing apparently goes back to Doug Englebart's Mother of All Demos in 1968:

https://en.wikipedia.org/wiki/Etherpad

https://en.wikipedia.org/wiki/Collaborative_real-time_editor...

A video I watched a while ago claimed that Talkomatic was the first one