What is KUVRT
Private chat that stays yours.
KUVRT is a free, private messenger that runs in your web browser. Messages, photos, voice messages and files are end-to-end encrypted, so only you and the person you write to can read them. It needs no phone number and no email address, and your chats are kept only on your own devices.
KUVRT at a glance
- Account
- No phone number and no email address. Your KUVRT is made on your device, and a recovery phrase brings it back.
- Encryption
- Messages, photos, voice messages and files are end-to-end encrypted. Only the people in the chat can read them.
- Keys
- Every message gets its own key, so old messages stay closed even if a key is ever lost.
- Post-quantum encryption
- Messages use a hybrid of X25519 and ML-KEM-768: each session starts with both, and re-keys with ML-KEM-768 after 50 messages or 7 days.
- Your chats
- Stored only on your devices, encrypted there too.
- The server
- It only passes sealed messages on, and deletes each one once it is delivered, at the latest after 45 days.
- Key checks
- A public key log lets the apps check that no key was swapped.
- Releases
- Every release is signed and recorded in that public log, and the app checks both before it installs an update.
- Ads and tracking
- None. No ads, no tracking, no code from anyone else.
- Price
- Free. Tips keep it running.
- Works on
- Any modern browser on a phone, a tablet or a computer. It installs like an app.
- Devices
- Up to five devices per person, linked to each other.
- Who runs it
- kaiserbyte in Vienna, Austria, on servers in Germany, in the EU.
How KUVRT differs
Nothing to sign up with
There is no phone number or email address to give. Your KUVRT is made on your device, and people reach you through an invite link you send them.
Your history is not on a server
Your chats live on your devices, not in an account somewhere else. The server holds a sealed message only until it is delivered.
Keys you can check
A public key log records the keys, so the apps notice when one was swapped. You can also compare a safety code with the person you write to.
The app checks itself
Every release is signed and published in the same public log, and the app installs an update only when both checks pass.
Nothing else inside
No ads, no trackers, no analytics service and no code from anyone else. KUVRT talks only to its own server and, when notifications are on, to your browser's push service.
No store needed
KUVRT runs in any modern browser and installs from there like an app, on phones and computers alike.
Questions
Is KUVRT free?
Yes. KUVRT is free to use and shows no ads. Tips from people who use it keep it running.
Do I need a phone number or an email address?
No. Your KUVRT is made on your device. Save your recovery phrase: it brings your KUVRT back on a new device.
Can KUVRT read my messages?
No. Messages are locked on your device before they leave it, and only the person you write to can open them. The server only passes sealed messages on.
Where are my chats stored?
Only on your devices, encrypted there too. Link a second device or export your chats now and then, so a lost phone does not take them with it.
Which devices does KUVRT work on?
Any modern browser on an iPhone, an iPad, an Android phone or a computer. Add it to your home screen to use it like an app, and link up to five devices.
Who runs KUVRT?
kaiserbyte, in Vienna, Austria. The servers are in Germany, in the EU.