Sentos Privacy Policy

Last updated October 1, 2026.

1. Introduction

This policy explains what information about you the Sentos service (“we”) processes, why, and how you can control it.

1.1. Principles

We don't sell data and don't show ads. We store only what the messenger cannot work without. We cannot read your personal chats and groups: they are encrypted on your devices, and we don't have the keys.

1.2. Terms of Service

By using Sentos you accept the Terms of Service, which include this policy.

2. Legal grounds

We process data because it is necessary to provide the service you asked for (the Terms of Service), and because we have a legitimate interest in keeping the service secure: protecting it against hacking, spam and abuse.

3. What data we use

3.1. Basic account data

Your username, display name, bio and profile photo. Other users can see them so they can find and recognize you; who sees optional details is up to you in the privacy settings.

3.2. Optional data

Phone number and email — only if you added them yourself.

3.3. Password and sign-in

Your password never leaves your device: the device derives a sign-in key from it, and we store only a verification hash of that key. For each session we store the device model and system, app version, sign-in time and IP address. We store only the public part of your passkeys.

3.4. Your messages

3.4.1. Personal chats and groups

Text, photos, videos, voice messages, moments and files are encrypted on the sender's device and can only be opened on the recipients' devices. The server stores ciphertext that we cannot open. To deliver messages, the server knows who sent a message to which chat and when, the message type (text, photo, voice and so on), its size and number of attachments, and delivery and read receipts.

3.4.2. History archive

So that your history opens on new devices, the app keeps an archive of it on the server. It is encrypted with a key derived from your password, recovery phrase or passkey — we cannot open it.

3.4.3. Channels

Channels are public by nature: their posts, names and descriptions are stored on the server unencrypted. So are group names, descriptions, photos and member lists.

3.4.4. Calls

Audio and video are encrypted between devices. If a call is relayed through our server, it passes on ciphertext without opening it. We store who called whom, when, how long the call lasted and how it ended, plus a technical connection log without names or content.

3.5. Contacts

We store your contact list inside Sentos — only people you added yourself — and your block list. We never upload your phone's address book.

3.6. Notifications

To deliver notifications, we store your devices' push tokens. Notification text is encrypted with your device's key — neither we, nor Apple, nor Google can see it.

3.7. Location and cookies

We do not collect your location. The web version does not use tracking cookies: it keeps encryption keys in your browser.

4. Keeping your data safe

4.1. Storage

Our server is located in a data center in the Netherlands (European Union). Only the Sentos team has access to it.

4.2. End-to-end encryption

The content of personal chats, groups, calls, the history archive and notifications is encrypted so that nobody but the participants can open it — including us.

4.3. Retention

• Account, groups, posts, contacts — until you delete them.
• Messages — until they are deleted.
• Server technical logs — up to 90 days; web server logs — 14 days.
• Backups — up to 30 days; they leave the server only encrypted.
• Reports and records of actions taken — as long as needed to keep the service safe.

5. How we process data

5.1. Running the service

So that you can sign in from different devices, chat, call and receive notifications.

5.2. Security

To protect accounts against hacking: limiting sign-in attempts, showing you your sessions and letting you end others.

5.3. Spam and abuse

We review user reports within 24 hours. Conversations are encrypted, so when you report messages you reveal the key of exactly those messages to moderators, and the server keeps their text — the report screen warns you about this. We have no other way to read conversations.

5.4. No ads

We don't show ads and don't use your data for advertising. The apps contain no third-party analytics or trackers.

6. Who your data may be shared with

6.1. Other Sentos users

Your profile and what you send go to the people you write to and to the members of your groups and channels.

6.2. Providers the service cannot work without

Apple, Google and browser push services deliver notifications: they know your push token, and the text reaches them encrypted. Our hosting provider in the Netherlands supplies the server hardware.

6.3. Law enforcement

Only in response to a lawful request and only what we have. We do not have the content of encrypted conversations.

7. Your rights

7.1. Rights

You can ask what information we hold about you, correct it, delete your account, restrict or object to processing, and complain to the data protection authority of your country.

7.2. How to exercise them

Most of this can be done right in the settings. For anything else, write to support@sentos.me; we reply within 30 days.

7.3. Settings

In the privacy settings you decide who can see your phone number, last seen time and public profile card, who can call you and add you to groups, and whom to block.

8. Deleting data

8.1. Account

Settings → Privacy and Security → “Delete Account”. This deletes your profile, keys, sessions, contacts, personal chats — for both participants — and your messages in groups. Groups you own pass to their admins or members. What remains: your @username, reserved so that nobody can impersonate you; a deletion record in the admin log; reports that mention you. See Account deletion.

8.2. Messages

You can delete your own messages for everyone in the chat, and clear a chat's history for yourself.

9. Changes

We will notify you in the app about significant changes to this policy. The date of this version is at the top.

10. Questions

Privacy questions — support@sentos.me. Support — sentos.me/en/support.