Swiss-made · your data stays in Switzerland
The Swiss messenger — also on your own server.
End-to-end encrypted, hosted in Switzerland at Infomaniak — or on-premise, wherever you want.
Download on theApp Store
Get it onGoogle Play
Ask about on-premise
All data stays in Switzerland.
Everything Swiss-made: your messages live on the kurznachricht server at Infomaniak — or, if you self-host, exactly where you want them.
YOUR DEVICE
kurznachricht App
Messages and pictures, end-to-end encrypted.
E2E encrypted
SWITZERLAND 🇨🇭
kurznachricht-Server
Hosted at Infomaniak — or on-premise on your own infrastructure, wherever you want.
ONLY EXIT № 1 — ONBOARDING
One verification SMS — sent via the Swiss provider aspsms.ch.
ONLY EXIT № 2 — PUSH
Wake-up push via FCM with a minimal payload: sender ID and recipient ID only — no content.
TECHNICAL ARCHITECTURE
The whole architecture is transparent — so you (or your IT team) can audit it.
SWISS SERVER · DEBIAN
Flutter-App
keys · local
Flutter-App
en-/decrypts
TLS
Caddy
HTTPS
:8080
Serverpod (Dart)
relay · zero-knowledge
Auth · Profile · Key
Message · Media
Push · Retention
Message · Media
Push · Retention
SQL
PostgreSQL
Profile · Keys
files
Media
ciphertext only
FCM (Push) · SMS-Gateway
CRYPTOGRAPHY
Scheme
X25519 + HKDF-SHA256 + AES-GCM-256 (envelope, fresh key per message)
Images
random key per image, «wrapped» to the recipient
Private key
on the device only (Keychain / Keystore)
Verification
manual key fingerprint
DATA & OPERATIONS
Plaintext
plain phone number, display name, avatar, public key, push token
Content
cipher message text and images — unreadable to the server
Retention
10 days, then hard-deleted server-side
Stack
Caddy · Serverpod 3.4.10 · PostgreSQL · TLS (Let's Encrypt)
Third parties
Google FCM (content-less wake push), SMS gateway (login code)