Just from a cursory (ha) glance, I see Websockets in dev console. Wouldn't be surprised if this is other viewers on the page.
EDIT: It's a web component on the page that does exactly this.
EDIT: It's a web component on the page that does exactly this.
Good find! That's a slightly older version that I'm moving. Here's a better version, complete with instructions on how to embed it in your own site
https://github.com/genmon/interconnected-cursor-party
It's a fork of the upstream PartyKit versions (I've added shared text highlights)
https://github.com/partykit/cursor-party
PartyKit is genuinely the best way to build real-time super scalable apps in very little code, multiplayer included. I have a contract here rn but I was a fan and user first. It's my go-to for most projects now: