The name suggested me that it was Nostr based, but an email is required to sign in, I haven't seen a way to use it with a Nostr extension or even a nsec key.

Also, I haven't seen if it's possible to self host it. I don't use any cloud storage or app, for I don't want to trust anybody with my data. Encrypted self hosting data is the way to go to self sovereignty, in my opinion.