NostrSync will be a PWA version of my  'Nostr Backup service," designed to run in the background. 

Once you turn it into a PWA, press the "backup & broadcast" button, and minimize it.

This will fetch, download, and broadcast your data in the background. All of this happens without the need for a server.

NostrSync PWA: https://nostrsync.live
https://image.nostr.build/83273803cd44d3b32589e222e8b4cc136520a5c9acf08b1dc7bfa39cf05d49d6.jpg