[prabhaav]

The message data is encrypted client side and stored in a cloud service of your choice (dropbox, s3, google, azure: default).

We don't host any data, it's stored in the users data store; the user controls all their data.

[voxadam]

Would it be possible to shard the encrypted data across multiple backends (e.g. across multiple providers or across multiple accounts on a single service)? It might be useful/interesting/fun to use erasure coding to increase redundancy and availibiliy.

[prabhaav]

Yes, people can redundantly shard their data to multiple cloud storage services. We plan on offering such a service if there is demand for it.