When the network is down, messages go from hand to hand

Pyrsos is a free app for Android phones. It sends messages by passing them from phone to phone over Bluetooth, like the fires that were once lit from hilltop to hilltop.

You Neighbour Passer-by Your mum

Example. There is no signal. You write to your mum, who lives on the other side of town: “I’m fine.” The message goes to a neighbour’s phone, then to a passer-by heading her way, and reaches her. None of them can read it, or even see that it is for her.

Four steps. Do the first two now, while everything still works.

STEP Get the app

From here while there is internet, or from someone who has it.

STEP Add your people, in person

You meet, and each of you scans the QR code on the other’s screen. Do it with your family and friends before you need it.

STEP Write your message

Pyrsos seals it in an envelope that only the recipient can open. Like a sealed letter: whoever carries it cannot read it.

STEP It travels from pocket to pocket

It passes over Bluetooth to nearby phones that have Pyrsos, even in a pocket, until it arrives. The more people have it, the faster. It can take minutes or days.

No internet needed. It cannot even go online. You don’t make an account.

It never asks where you are. It does not ask for your location, now or ever.

Every phone has its own code, 12 characters long, that never changes and cannot be copied. If two of your friends have the same name, the code shows who is who. When you add each other, check together that it matches.

It works while closed. It helps messages along even when you are not looking at it. You only see a small notice, which never shows messages. It stops by itself when the battery is low, and you can stop it in Settings.

Get Pyrsos

It is free.

If you have internet today, don’t wait. Download it now, and when the time comes you can pass it on to others too.

When you open it, your phone will ask whether to allow installs from an “unknown source”. That is normal, because Pyrsos is not on Google Play. Tap “Allow”.

Anyone who already has Pyrsos can pass it to you from their phone, over Bluetooth. Then you can pass it on to others too. If you get it from someone you do not know, check that it is the real one.

Tip: save this page on your phone. It opens without internet too.

The app Obtainium installs apps straight from where they are published, and tells you when a new version is out. To have it keep Pyrsos up to date:

Android installs an update only if it is signed with the same key as the Pyrsos already on your phone. So no update, wherever it comes from, can swap your Pyrsos for someone else’s app.

Someone could hand out a fake Pyrsos to spy on the people who install it. What sets the real one apart is its signature: a digital fingerprint nobody else can make. If you get it from someone you do not know, check it before you install it.

The fingerprint of the real Pyrsos (SHA-256):

An app cannot vouch for itself: a fake Pyrsos could show the right fingerprint on its own screens. That is why the check goes through AppVerifier or apksigner, which read what the system itself holds.

apksigner verify --print-certs pyrsos.apk

The SHA-256 digest line shows the same fingerprint, in lower case and without colons. It must read exactly:

What it keeps safe and what it does not, without overselling.

Pyrsos is free and will stay free. If you like, you can send a small donation. Tap “Copy” next to an address.

Careful: payments in Bitcoin, Ethereum and Solana stay public forever. If that puts you at risk, use Monero, which does not show publicly who paid, or do not send. You can help without money too: give Pyrsos to the people close to you, and add each other now.

The code of Pyrsos is open: anyone can read it and check it. It is free software under the GNU GPL, version 3 or later, and it costs nothing.

Are you a developer and want to help? Open an issue on GitHub.

The app has no internet permission, so it cannot send anything to anyone, us included. It has no accounts, no ads and no counters. This site has no cookies or counters either.

Pyrsos is provided as it is, with no warranty of any kind. To the extent the law allows, we accept no liability for any harm or loss from using it.