Technically the relays. But you can back it up and run your own relay too.
Discussion
good to know, thanks for this
Best resources on best way to run your own relay?
Umbrel has an app to do it in few clicks.
nostr:npub1utx00neqgqln72j22kej3ux7803c2k986henvvha4thuwfkper4s7r50e8 also has an awesome service that lets you run your own private relay to backup your notes. They handle everything and make it seemless Relaying.io
Thanks I'll check it out