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The Petra family

Apps that stay private.

Private. No ads. No data sales.

Petra is a family of apps for the things that are nobody else’s business: your conversations and your passwords. Encryption always happens on your device.

The Petra apps

Each app works on its own. Only the account and subscription infrastructure is shared, and only where it is needed. More apps are coming.

  • Petra Messenger

    Available

    The messenger that does not read along.

    Messages, files and voice messages are encrypted on your device. The server only forwards what it cannot open.

    • End-to-end encrypted
    • Groups, threads and voice messages
    • In the browser, on Android and iPhone
  • Petra Shield

    Coming soon

    The vault for passwords, 2FA codes and API keys.

    Your vault is encrypted with AES-256-GCM on your device and stays there. No Petra server sees your passwords.

    • Unlock with Face ID, Touch ID or fingerprint
    • Codes and passwords above the keyboard
    • Leak check without sending your password

Petra MessengerAvailable

Your conversations belong to you.

Petra encrypts every message on your device. Only you and the person you're talking to can read it. The server only forwards what it cannot open.

Runs in the browser. Installable as an app on Android and iPhone.

Why Petra?

Petra is Greek for “rock”. This is what the app is built on:

  1. Privacy

    Your conversations belong to you. We do not sell data.

  2. End-to-end encrypted

    Messages, files and voice messages are encrypted on your device. We cannot read them.

  3. Trusted

    We earn trust with openness: you see what the server sees.

  4. Rock-solid

    Stable and dependable, like a rock.

  5. Ad-free

    No ads, ever. Petra lives on extras, not on your data.

More than writing messages.

Threads instead of chaos

Reply to a message in its own thread. The group stays tidy, even when ten people write at once.

Messages that disappear

Set a timer per chat. Afterwards, messages and attachments are also deleted on the server.

  • Groups with roles

    Admins manage members. Whoever joins or leaves appears as a line in the chat.

  • Draw together

    Sketch together in real time, right next to the chat.

  • Voice messages

    With waveform, speed control and optional text to read along.

  • Invite by link

    One link, valid for seven days, usable once. You decide who gets in.

Verifiable, not just promised.

Every chat has a safety number. It is identical for you and the person you're talking to. Compare it in person or over the phone. If they match, nobody is listening in.

In each chat's info panel, Petra also shows the last packet your device sent to the server.

Safety number (example)

Petra ShieldComing soon

Your passwords stay with you.

Petra Shield is a vault for passwords, 2FA codes and API keys. It is encrypted with AES-256-GCM on your device and stays there. You unlock it with Face ID, Touch ID or fingerprint. No account and no Petra server. With Pro, it syncs via iCloud between iPhone, iPad and Mac.

Available now via TestFlight for iPhone. Soon on the App Store and Google Play.

Sync between iPhone, iPad and Mac via iCloud, end-to-end encrypted, without a PETRA server. The Mac app is coming soon.

  • Autofill above the keyboard

    Codes and passwords appear above the keyboard, without switching apps. From iOS 18 and via Android autofill. In Pro.

  • Authenticator built in

    Scan a service’s QR code. Shield shows the six-digit codes (TOTP) right next to the password.

  • Password generator

    Long, random passwords with one tap. You do not have to remember them.

  • Leak check

    Shield checks whether a password appears in known data leaks, without revealing it.

You can import from Google Authenticator (migration QR), Apple Passwords, Chrome, Bitwarden, 1Password, LastPass, Firefox, Dashlane, Proton Pass, KeePass, Aegis and 2FAS. You keep the encrypted backup file yourself.

k-anonymity

The leak check never learns your password

Shield computes a SHA-1 hash of the password on your device and sends only its first 5 characters to Have I Been Pwned. What comes back is a list of all known hashes with that beginning. The comparison happens on your device.

SHA-1 hash (example)

Leaves your device
The first 5 characters
Stays on your device
The rest of the hash and your password

14 days, everything free

After that, you stay on Free or switch to Pro.

Free

No charge

  • Up to 3 entries
  • 2FA codes in the app

Pro

€2.49 a month or €19.99 a year

  • Unlimited entries
  • Autofill above the keyboard
  • Automatic leak scan
  • iCloud sync between iPhone, iPad and Mac

Subscriptions run through the App Store or Google Play.

Frequently asked questions

What is Petra?

Petra is a messenger that protects your conversations with end-to-end encryption. We cannot read your messages. There are no ads, and we do not sell data.

What does “Invite friend” mean?

You create a personal link and send it to someone you know. The link is valid for seven days and works exactly once. Whoever opens it and signs up is in. After that, the link is used up. You can create a new one at any time.

Why is an invite link only valid for seven days and only once?

This way, you stay in control of the link. It cannot be found later, passed on to many people, or shared online for good. You decide who comes in.

Can Petra read my messages?

No. Messages, files and voice messages are encrypted on your device. The server only sees that something arrives, who sent it and how big it is, but never the content.

What is the security number?

It consists of twelve groups of numbers and is the same for each pair of people. Compare it, ideally in person or by phone call. If the numbers match, nobody is secretly reading along.

What happens if I lose my phone or switch to a new one?

When you first start Petra, it shows you a recovery code. With it, you can read your chats on a new phone. Keep it safe. We cannot show or replace it.

How does Petra make money?

Petra is funded by an affordable, optional subscription for extra features. Chatting and security stay free. The subscription pays for maintenance and new features. This is how we manage without ads and without selling data. Right now, everything is free.

What data does Petra store?

Your account (name, username and, if you wish, your phone number), encrypted messages until they expire or are deleted, and your push registration. We do not use analytics or advertising tools.

What are self-destructing messages?

For each chat, you can set a timer, for example from 30 seconds to one day. After that, the messages are deleted from the devices and from the server.

Where are the servers located?

In Nuremberg, Germany, at Hetzner Online. The operator is a Dutch company in Amsterdam (see the imprint).

How do I delete my account?

Open Settings and tap “Delete account” at the bottom. Your account, your key and your backup will be removed. This cannot be undone.

What is the public profile page?

At getpetra.io/@dein-name, every person has a small page with their name, a description and, if they have one, the blue check. With the link, others go straight to your chat. To chat and to connect with you, they need a Petra account. The page does not show up in search engines. You can switch it off at any time under Settings, Privacy & security.

Why can’t I use this username?

Names of brands, well-known people and inappropriate words are protected so that nobody can pose as someone else. Choose a different name. If the name really is yours, sign up with a different name and write to Support in the app. We will check it and release the name.

How do I create my own stickers and GIFs?

Open Settings, My stickers, create a pack and add images or GIFs. Images are cropped to a square automatically, GIFs can be up to 1 MB. In the chat, you send them with the sticker icon next to the text field. You can keep received stickers in your “Saved” pack with “Keep”. Your stickers are only stored on your device.

How long are documents kept?

The server deletes documents such as PDFs and other files after 3 days, which saves space and data. If you want to keep a document, download it to your device beforehand. Photos, videos and voice messages are not affected.

How do I contact support?

Open Settings, Help & Info, Support and write to us there. We reply directly in the app.

What is Petra Shield?

Petra Shield is a vault for passwords, 2FA codes and API keys, as an app for iPhone and Android. The vault is encrypted with AES-256-GCM on your device and stays there. Available now via TestFlight for iPhone, soon on the App Store and Google Play.

Does Shield need an account?

No. Shield has no account and no Petra server. The vault lives on your device. With Pro, you can sync it across iPhone, iPad and Mac via iCloud, end-to-end encrypted. Android has no sync.

What does Shield cost?

For 14 days, all features are free. After that you stay on Free with up to 3 entries, or choose Pro for €2.49 a month or €19.99 a year.

Does Petra see my passwords?

No. The vault is stored encrypted on your device. No Petra server sees your passwords.

How does Shield check passwords for data leaks without sending them?

Shield computes a SHA-1 hash of the password on your device and sends only its first 5 characters to Have I Been Pwned. What comes back is a list of all known hashes with that beginning. The comparison happens on your device.

Start with the messenger. It takes a minute.

Shield is available now via TestFlight for iPhone. Soon on the App Store and Google Play.

Open Petra