SimpleX Chat stores all user data only on client devices using a portable encrypted database format that can be exported and transferred to any supported device.

The end-to-end encrypted messages are held temporarily on SimpleX relay servers until received, then they are permanently deleted.

Unlike federated networks servers (email, XMPP or Matrix), SimpleX servers don't store user accounts, they only relay messages, protecting the privacy of both parties.

There are no identifiers or ciphertext in common between sent and received server traffic — if anybody is observing it, they cannot easily determine who communicates with whom, even if TLS is compromised.