Rethinking what
a messenger should be.
Privacy is a human right. Kasumi is built around three principles: your messages belong to you, speed matters, and honest monetisation through subscriptions - never your data.
Signal Protocol
Every message encrypted with Double Ratchet + X3DH. The gold standard in end-to-end cryptography.
Built for Speed
Go backend, persistent WebSocket connections, global infrastructure. Messages arrive before you expect them.
No Ads. Ever.
Subscription and donations only. Your conversations are never the product.
Media & Files
Photos, videos, voice messages - encrypted end-to-end with unique keys per file before leaving your device.
Global Infrastructure
Distributed nodes across multiple regions. Your nearest server is always just milliseconds away.
5 Beautiful Themes
Crimson, Sakura, Obsidian, Void, Kasumi. Make it yours.
Your key.
Your messages.
Your private key is generated on your device and never leaves it. Every message is encrypted before it travels. Our servers see only bytes they cannot read.
Keys generated on your device
Your private key is created locally and never leaves your phone. We never see it, store it, or have access to it.
Every message uniquely encrypted
Double Ratchet generates a new encryption key for every single message. No two messages share a key.
Only your recipient can decrypt
Our servers route encrypted bytes they cannot read. Even if compromised, your messages remain private.
Nothing to hide.
Everything to protect.
Replay Attack Protection
Every message carries a unique nonce and timestamp. Intercepted messages cannot be replayed.
Certificate Pinning
The iOS app rejects any certificate not matching ours. Man-in-the-middle attacks are not possible.
Forward Secrecy
Past messages stay encrypted even if current keys are compromised. Double Ratchet guarantees it.
Minimal Metadata
We store the least possible information about who talks to whom. Your social graph is yours.
Be first in
the mist.
Kasumi is coming to iOS first. Join the waitlist and help us shape what private messaging should look like.
A few questions. Helps us build what you actually need.
You're in the mist.
We'll reach out when Kasumi is ready for early access.
Thank you for being here from the very beginning.
Support the
project.
Kasumi is built independently - no investors, no ads, no VC money. If you believe in private messaging, every contribution helps keep it that way.
