Syncing contacts over usb cable

[Ralf]

There is another discussion about this, maybe take a look there:

Offline synchronization

For real P2P (serverless), Syncthing (files) + DecSync CC (contacts & calendar) should get you started. No need for a server setup. Generally I would wish to see /e/ provide DecSync-style file-based alternatives to any online features. This way, the user can freely decide whether to use server-based solutions (/e/'s or their own), P2P or to sync/backup even completely offline (USB) without any loss of features.