The fun thing is that in some way it's a bit inaccurate. We auto port-forward ports from the remote machines to your localhost, so you can still just go to localhost:3000 or whatever, and it goes to whatever machine you have selected in the desktop app. We'll give you a browser in the mobile app too soon to hit "localhost" on mobile.
I do provide cloud support for somethings like embeddings and crawling, but you can run it local if you want. The only thing closed source is the memory system, but it still runs local if you want it.