Sign up without a phone number or email
To create an account you choose a username and a password. Umbera does not ask for a phone number, an email address or access to your address book, so there is nothing that links the account to your SIM card or your real name.
Instead of a number you get a quant address. It is derived from your ML-DSA (Dilithium) signing key, the way a crypto wallet address is derived from a key. You can share it so people can add you, and it reveals nothing about who you are.
The server does not know who talks to whom
Being anonymous to other people is not enough if the service itself can see your contacts. In Umbera the sender of a message is sealed inside the ciphertext (sealed sender), so the server accepts an envelope without knowing who sent it.
Messages are delivered to a mailbox address that only you and the other person can derive. It changes periodically, so conversations cannot be linked to each other by address. Message size is padded to blocks, so the length of the text is hidden too.
In group chats the server does not know that it is a group or who is in it: group keys are agreed using MLS (RFC 9420).
Hide your IP address with built-in Tor
Your IP address can reveal where you are. Umbera has Tor built in: one switch in the network settings routes all of the app’s traffic through the Tor network.
For calls there is a separate “Hide IP in calls” option. The call then goes through a relay, so the other person never sees your IP address, and the relay only ever sees encrypted packets.
Recover your account with a recovery phrase
Without a phone number there is no SMS code to get back in, so Umbera uses a recovery phrase, like a crypto wallet. Keep it safe: with the phrase you can restore the account on a new device, and without it nobody — including us — can restore it for you.
Anonymous, but still end-to-end encrypted
Anonymity and encryption work together. Every message, photo, video, file and voice note is encrypted on your device, and only the recipient can decrypt it. Each envelope is sealed with two algorithms at once — the classic X25519 and the post-quantum ML-KEM-1024 — so reading it would mean breaking both.
The cryptographic core is open source, and the proof page shows tests that anyone can run to check these claims for themselves.
Frequently asked questions
Is Umbera really anonymous?
You sign up with a username and password only — no phone number, no email and no address book. The server does not see who sends a message, and the delivery address changes over time. To also hide your IP address from the network, turn on the built-in Tor.
Can I use a messenger without a phone number?
Yes. Umbera never asks for a phone number. People add you by your username or your quant address.
What does the Umbera server know about me?
The server stores your username, your public keys and the encrypted envelopes it has to deliver. It does not see the content of messages, who sent them or who you talk to. It does need the time of a message to deliver it.
What happens if I forget my password?
You restore the account with your recovery phrase. There is no SMS or email reset, because there is no phone number or email on the account.
Is Umbera free?
The app is free to download from Google Play and the App Store and starts with a free trial, no card required. After the trial you can subscribe in the store.
Try Umbera
Available on Android and iPhone. The trial is free and starts on first launch — no card required. See exactly what the server can and cannot see on the proof page.