compare

The architecture is the privacy policy.

Cloud messengers promise not to look. FLVSH removes the place where looking happens: no servers, no accounts, no copy of anything outside your phone.

cloud messengers vs flvsh

property	cloud messengers	flvsh
Infrastructure	Their servers, their uptime, their rules	No servers: the phones in the room are the network
Identity	Phone number or email required	X25519 keypair generated on device — no signup
Works offline	Dead without internet	Built for airplane mode: BLE only, end to end
Metadata	Who, when, how often — logged server-side	Nothing to log with: traffic never leaves the mesh
Encryption	E2E, but the operator routes every byte	Post-quantum PQXDH + Double Ratchet; relays see only ciphertext
Message history	Cloud backups you don't control	Local SQLite only, with disappearing messages
Range	Global, while the grid is up	The room by radio, the crowd by mesh relay

Infrastructure
cloud messengers
Their servers, their uptime, their rules
flvsh
No servers: the phones in the room are the network
Identity
cloud messengers
Phone number or email required
flvsh
X25519 keypair generated on device — no signup
Works offline
cloud messengers
Dead without internet
flvsh
Built for airplane mode: BLE only, end to end
Metadata
cloud messengers
Who, when, how often — logged server-side
flvsh
Nothing to log with: traffic never leaves the mesh
Encryption
cloud messengers
E2E, but the operator routes every byte
flvsh
Post-quantum PQXDH + Double Ratchet; relays see only ciphertext
Message history
cloud messengers
Cloud backups you don't control
flvsh
Local SQLite only, with disappearing messages
Range
cloud messengers
Global, while the grid is up
flvsh
The room by radio, the crowd by mesh relay

The cryptography is deliberately boring: a PQXDH handshake (X25519 plus ML-KEM-768) feeding a Double Ratchet, with ChaCha20-Poly1305 authenticated encryption from well-established RustCrypto implementations, in one shared Rust core compiled into both apps. No novel primitives, no proprietary protocol. Just a network made of the phones themselves.