The most common objection
'If there's no server, what happens when my phone is off? Do I lose messages?' It's the most common question. And it's legitimate. In an app with a central server, messages are stored on the server until you connect. It doesn't matter if your phone is off for three days — when you turn it on, everything is there. That convenience has a price, but it undeniably works.
Solo2 doesn't have a central server. Messages go directly from one device to another. If your phone is off, nobody collects messages for you. That's true. But there's a solution that doesn't require giving up anything.
The second device
Imagine you have Solo2 installed on your phone and also on your home or office computer. Nothing special to install — just having solo2.net open in a browser tab is enough. If you sign in with the same user on both devices, Solo2 connects them automatically and syncs everything: messages, files, contacts, settings.
Now imagine your computer is on during the day with that tab open. While you go out with your phone, your computer stays there. If someone sends you a message and your phone has the app sleeping or no signal, your computer receives it. When you get home or your phone regains connection, it automatically syncs with the computer and you have all your messages.
Your own server, under your control
In practice, your computer is acting as a personal server. But with one fundamental difference: it's your machine, in your home, under your control. It's not a data center from a company in another country. It's not a cloud managed by someone else. It's your computer. Your data is on your hard drive, encrypted, accessible only by you.
This gives you an experience similar to any app with a central server — messages always reach one of your devices — but without giving up any of Solo2's privacy guarantees. Everything remains end-to-end encrypted. Everything remains peer-to-peer. Nobody else has access.
What gets synced
Everything. Text messages, files sent to you, voice messages, images, GIFs. Also contacts, active tunnels and visual settings. If you change the theme on your computer, when the phone connects it will appear with the same theme. You don't have to configure anything or do manual transfers. Solo2 detects that there are two devices with the same user and syncs them automatically.
One detail to keep in mind
Some browsers, to save battery or resources, may pause tabs that have been inactive for a while. If that happens, Solo2 resumes automatically when the tab becomes active again — but while paused, it doesn't receive messages. If you use your computer as a permanent node, it's worth checking that your browser isn't sleeping the Solo2 tab. In most browsers you can pin the tab or disable automatic suspension in settings.
The difference with the cloud
When an app backs up to the cloud — iCloud, Google Drive — your data leaves your device and is stored on servers you don't control. Someone manages those machines. Someone has the access keys. Someone can access that data if asked, or if stolen.
With Solo2, your data never leaves your devices. Synchronization is direct between your phone and computer, encrypted with the same keys used in a normal conversation. No intermediate step. No copy on any external server. Your second device is your backup — and it's the only backup that exists.
One thing to keep in mind: synchronization is bidirectional. If you delete something on one device, it disappears on the other. To protect yourself against extreme situations, combine synchronization with periodic backups of your vault from the Solo2 menu. Synchronization gives you availability. The backup gives you the safety net.
It's not a limitation. It's a design decision. And for many people, it's exactly what they need.