The app is free, and it installs straight from the browser — no app store, nothing to download or pay for. You get a real app icon, full-screen journaling, and Face ID / fingerprint sign-in.
The Solous icon appears with your other apps. Face ID works for signing in with your passkey.
On Android, choose your browser before you install. An installed app keeps running inside whichever browser installed it — install from Samsung Internet and you get a Samsung app, install from Chrome and you get a Chrome one. Changing your phone’s default browser afterwards does not change it, and the two don’t share a sign-in, so you’ll log in again if you switch. If face or fingerprint sign-in gives you trouble, uninstall and reinstall from Chrome.
Use “Install as app”, not “Add page to → Home screen”. The second one doesn’t reliably install Solous — it can just save a bookmark that reopens the browser, which looks exactly like nothing happened. Samsung Internet is the default browser on Galaxy phones and words all of this differently from Chrome, so the option is under the three bars rather than a ⋮ menu.
Whatever already unlocks your phone — fingerprint, face, PIN or pattern — works for passkey sign-in.
Solous opens in its own window, like any desktop app.
Everything stays in sync — the app and the website are the same journal, always up to date, protected the same way.