Umbera
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Umbera™

A messenger where the server doesn’t know who talks to whom

Umbera is an anonymous, end-to-end encrypted messenger. Sign up with a username and password — no phone number, no email. Messages, files and calls are encrypted on your device, including with the post-quantum ML-KEM-1024.

3 days free, no card requiredActivation code for Android

What you see and what the server sees

The same conversation. On the right is everything Umbera’s server knows about one of these messages.

Encrypted chat in the Umbera anonymous messenger
You see
The server sees
Sender
Not includedIt’s sealed inside the ciphertext
To
Mailbox 3f9c…a71eOnly the two of you can derive it, and it changes
Message
8a1f0c7ed3b294e6 51c0a9f27b3e8d14 f60b2c9a7e15d38c…
Size
Padded to a blockThe length of the text is hidden
Time
2026-10-17 14:03:12 UTCNeeded to deliver it

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 derived from your ML-DSA (Dilithium) signing key, like a wallet address. Share it to be added — it reveals nothing about you.

Umbera profile with a quant address instead of a phone number
Contacts in the Umbera private messenger

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.

Encrypted chat list in Umbera
End-to-end encrypted group chat

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.

Incoming encrypted call in Umbera
End-to-end encrypted video call

Network privacy is one switch away

Tor is built in. Route all traffic through Tor with a single switch.

Hide IP in calls. Calls go through the relay, so the other person never sees your IP address.

Umbera privacy settings
Built-in Tor in the Umbera messenger

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

Don’t trust us. Verify.

The code, the tests and the traffic checks are public. Anyone can repeat every step.

Diagram: how a message is sealed

Only the recipient can read a message

  • Every message is sealed on the sender’s phone with X25519 + Kyber (ML-KEM-1024) 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.
Details →
Diagram: call encryption through the relay

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.
Details →
Open the proof on GitHubRead the full breakdown

Getting started

Today
Install the app

From Google Play or the App Store. Sign up without a phone number.

3 days
Use it for free

The trial starts automatically on first launch. No card required.

After that
Subscription or code

Subscribe in Google Play or the App Store. A code bought on this site works only in the Android app from Google Play.

Pricing and activation code
Umbera

Install Umbera

The first 3 days are free. No card required.

Get it onGoogle PlayDownload on theApp Store