A new design
Eclipse phases in every screen, dark and light themes, a new logo.
A messenger where the server doesn’t know who talks to whom
Umbera is an anonymous, end-to-end encrypted messenger. Sign up with just a username and password — no phone number, no email. Even our server can’t read your messages or tell who you talk to.
A free trial with everything open, then a few contacts free. No card requiredActivation code for Android
What’s new in Umbera 2.0
Every point below is in the app.
Vault
A hidden message in an ordinary photo or video, opened only with a key, with a time limit you choose.
About Vault
Reactions and comments in Communities
Reactions, polls and threaded discussions under a separate pseudonym in every channel.
About Communities
Shield shows real signals
It checks your phone itself and names what it found. On iPhone that includes signs of a jailbreak and an intercepted connection.
About Shield
Large files
Send large files. On Android a long transfer keeps going in the background, with progress and Cancel in the notification.
App lock and hidden names
A short code or pattern instead of the full password at sign-in. Notifications, including calls, can say only that something arrived.
Try it, then keep what’s free
A free trial with everything open, then a few contacts stay free for good. Encryption, Tor and Shield are always free.
Pricing1000
concurrent users on one server — zero losses
20 ms
median delivery latency under that load
800+
concurrent call streams on a single relay
ML-KEM
post-quantum encryption, open code and tests
Our own measurements, 21 October 2026: 1000 simulated apps sent encrypted messages and files to one server for 5 minutes; 800 call streams ran through one relay with 0.7% packet loss.
01
What you see and what the server sees
The same conversation as you see it, and everything Umbera’s server knows about one of these messages.
You see
The server sees
Sender
Not included
It’s sealed inside the ciphertext
To
Mailbox 3f9c…a71e
Only the two of you can derive it, and it changes
Message
8a1f0c7ed3b294e6 51c0a9f27b3e8d14 f60b2c9a7e15d38c…
Size
Padded to a block
The length of the text is hidden
Time
2026-10-17 14:03:12 UTC
Needed to deliver it
02
An account without a phone number
A username and password are all you need. No phone number, email or access to your contacts.
A quant address instead of a number. It’s your public ID in Umbera: a short code you share so people can add you. It’s made from your ML-DSA signing key, like a crypto wallet address, and reveals nothing about you.
03
Only you know who you talk to
The sender is sealed inside the ciphertext. The server accepts the envelope without knowing who sent it.
Only the two of you can derive the mailbox address. It changes periodically, so conversations can’t be linked by address.
Groups run on MLS (RFC 9420). The server doesn’t know it’s a group or who is in it.
04
Only the participants hear a call
DTLS-SRTP between devices. The keys never leave the phones.
The relay sees only ciphertext. It’s used when a direct connection isn’t possible, and it has no keys.
Group calls connect participants directly. There’s no server in the middle.
05
Network privacy is one switch away
Tor is built in. Route all traffic through Tor with a single switch.
Hide IP in calls. Turn this setting on and calls go through the relay, so the other person doesn’t see your IP address.
06
What’s encrypted and how
Messages
A Double Ratchet session first — keys change with every message. Then each envelope is sealed with two algorithms at once, so reading it means breaking both. Size is padded to blocks.
X25519 + ML-KEM-1024 · HKDF-SHA256 · AES-256-GCM
Groups
Group keys are agreed using the MLS standard.
MLS · RFC 9420
Files, photos, videos, voice notes
Encrypted on the sender’s device, with a separate key for each file. Metadata is removed from PDFs before sending.
AES-256-GCM
07
Don’t trust us. Verify.
The code, the tests and the traffic checks are public. Anyone can repeat every step.
Sealed sender, hybrid post-quantum
The sender’s identity travels inside the ciphertext. The relay sees neither sender nor recipient.
- 1. Ratchetencrypt the message
- 2. Inner packagesender + ratchet message
- 3. SealX25519 + ML-KEM
- 4. Padsize buckets
- 5. Deliverrendezvous ID
Seal key derivation
ss₁ = X25519(eph_priv, recipient_x25519)ss₂ = ML-KEM-1024.Encaps(recipient_kyber)k = HKDF-SHA256(ss₁ ‖ ss₂, salt = HYBRID_LABEL, info = "key-derivation", 64)[0..32]box = AES-256-GCM(k, iv₁₂, inner) → { ephemeralPublicKey, kyberCiphertext, iv, encryptedInner, authTag }Only the recipient can read a message
- Every message is sealed on the sender’s phone with X25519 + ML-KEM-1024 (formerly Kyber) and AES-256-GCM.
- The server receives only a mailbox address and ciphertext — no sender, no recipient.
- 7 tests show that any other key fails, breaking X25519 alone is not enough, and tampering is rejected.
Calls
Call keys are created on the two phones. The relay forwards encrypted packets it cannot open.
Your phonecreates call keys
SRTP, encrypted
Relayforwards ciphertext
SRTP, encrypted
The other phonecreates call keys
Why nobody in the middle can listen
- Audio and video are encrypted with DTLS-SRTP directly between the two phones.
- The keys never leave the phones. The relay and the network see only encrypted packets.
- Call setup (SDP and key fingerprints) is end-to-end encrypted and signed by the caller, then delivered through the same anonymous channel as messages.
- The server cannot read or change call setup, so it cannot slip itself in as a middleman.
Only the participants can hear a call
- Audio and video are encrypted with DTLS-SRTP directly between the two phones — keys never leave them.
- The relay forwards only encrypted packets and cannot open them.
- Call setup is encrypted and signed, so the server cannot become a middleman.
The cryptographic core is open source — verify it yourself: GitHub · crates.io
08
Getting started
Today
Install the app
From Google Play or the App Store. Sign up without a phone number and write down the 12-word recovery phrase: it’s the only way back if you forget your password.
Free trial
Everything is open
Every feature, from the first launch. No card required, and nothing to cancel.
After that
A few contacts free, for good
You choose which ones. With them you keep chats, files, calls and groups made up of those people. Other contacts stay readable, nothing is deleted.
Whenever you want more
Umbera Premium
Any number of people, any groups and conferences, Communities and a status badge. Subscribe in Google Play or the App Store. A code bought on this site works only in the Android app from Google Play.
CommunitiesIn the app
Channels where nobody knows who you are
Communities are in Umbera now: channels with a separate pseudonym in every channel, where nobody can see who runs a channel or who follows it. Next: Umbera for desktop and Umbera Business.
Install Umbera
A free trial with everything open, then a few contacts stay free for good. No card required.