Cloister brings WhatsApp, Discord, Gmail, Messenger and the rest into one lightweight app, with privacy you can switch on in a keystroke and focus sessions that hold the noise until you are ready.
Free and open source · Windows, macOS and Linux
cloister
WhatsApp
Try it: switch Veil off, or hover a chat to peek through it.
Works with the apps you already use
Privacy and focus, built in
Someone walks up behind you? Press Ctrl Shift P and every conversation blurs. Hover one chat to read it while the rest stay hidden. While Veil is on, notifications name the app but never the person or the message.
Start a session and Cloister quietly holds every notification. When the timer ends you get one calm summary of what came in, instead of forty interruptions. Important people can still get through.
Lock behind a PIN on start, after you step away, or on demand, and use Windows Hello where you have it. Pages are hidden, not just covered.
Rust and your system's own browser engine, no bundled Chromium. Idle pages go to sleep, and you can see what each one uses.
Native notifications that open the right service when clicked, unread badges, and a history of the last fifty. Hide the sender and text for any service you want kept private.
Every service keeps its own separate sign in on your computer. One click signs you out and wipes its data.
Themes
Warm graphite for late nights, crisp white for bright offices, and four more in between. Or let Cloister follow Windows and switch between light and dark on its own.
Every theme is checked for readable contrast.
Memory
Desktop chat apps each run a whole browser of their own, all day. Cloister runs every service in one shared engine, and lets the ones you only check now and then step back: paused apps are frozen and wake every few minutes to check for messages, asleep apps close until you open them.
1.1 GBmemory freed for your other apps
Not counted above: all services share one browser engine in Cloister, instead of one per app7.
Estimates. Each app's figure is a published idle measurement of its own desktop app on Windows; yours will vary with how many chats and servers you have. An awake service in Cloister is counted at the full cost of the desktop app, plus about 40 MB for Cloister itself5. Paused services count as freed because Windows may reuse a frozen page's memory6; asleep services are closed. Pause is available on Windows. Sources: 1 Windows Latest, WhatsApp 2 Tech2Geek, Discord 3 Windows Latest, Teams 4 Slack Engineering (low end of its range) 5 Tauri idle benchmark 6 Microsoft, WebView2 TrySuspend 7 Microsoft, WebView2 profiles
Download
Free, with no account to create.
.exe · or the .msi package
Cloister is not code-signed yet, so SmartScreen does not recognise it. Click More info, then Run anyway. You only do this once.
.dmg · one universal app
Cloister is not notarised by Apple yet. Open it once, then go to System Settings › Privacy & Security and click Open Anyway. If macOS calls it damaged, run:
xattr -cr /Applications/Cloister.appor .deb for Debian and Ubuntu, .rpm for Fedora
chmod +x Cloister_*.AppImage
./Cloister_*.AppImageOn macOS, each service keeps a separate sign in on macOS 14 and later.
FAQ
Yes. It is open source under the MIT licence. There is no paid tier, no ads and no account.
No. Each service runs as its normal website in its own private profile on your computer. Cloister only sees what a notification would show, uses it to display that notification, and never stores it on disk or sends it anywhere.
Most of them ship a full copy of Chromium. Cloister uses the browser engine your system already has (WebView2 on Windows, WebKit on macOS and Linux), so the Windows download is a few megabytes and idle pages can be put to sleep.
Yes. Cloister checks for new versions on start and every few hours, and shows an "Update" button when one is ready. Updates are signed, so only genuine releases install, and nothing changes until you click. Your services and sign ins stay as they are.
Please open an issue on GitHub with your system and what you saw. Pull requests are welcome too.
