Your Macs, in step

What syncs

• Display arrangements. The arrangements you save for each set of monitors, on any of your Macs.
• Workspaces and window layouts. Each other Mac's appear in Workspaces in their own group, under that Mac's name.
• Each Mac's displays. Their names, sizes and positions, with a small thumbnail of each desktop picture, so the Universal Control page can show every Mac's displays side by side and you can arrange another Mac's own displays from this one. Each Mac also shares its network hardware addresses, which waking it over the network needs.

To arrange another Mac's displays, choose Arrange Remotely next to it in Macs & Sync, or pick it from the menu at the top of Displays. Move its displays, then click Save for and that Mac's name. The new arrangement applies there as soon as it syncs.

What stays on each Mac

• Your license key and activation. They're kept in each Mac's Keychain. Each Mac uses one of your license's three activations.
• Scrolling Windows. Its settings and its saved sessions.
• The app's settings, such as shortcuts and the options under Settings.

How it works

• Directly between your Macs. They connect over your local network: Wi-Fi, Ethernet or a Thunderbolt cable between them. Nothing goes through a server.
• Found with Bonjour. Each Mac announces itself on the local network and looks for the others.
• Only your own Macs. Universal Display Magnet syncs only with Macs that Universal Control links to this one. It recognizes them by the identities Universal Control already gives them, so there's nothing to pair.
• Encrypted. Everything the Macs send each other is sealed with ChaCha20-Poly1305, under a key derived from the Macs' Universal Control identities.
• No account. You don't sign in to anything in the app. The email address you bought with is used only for your purchase.

The privacy policy lists every connection the app makes.

Set it up

1. Install and activate Universal Display Magnet on each Mac.
2. Link the Macs once with Universal Control, under System Settings → Displays → Link to Mac or iPad.
3. Allow Local Network access on each Mac when macOS asks.

Sync with my other Macs in Macs & Sync is on from the start. The bottom of the sidebar shows "Synced with" and the other Macs' names once they're connected. The guide Universal Control between Macs goes through it step by step.

If the Macs don't find each other, open Connect by address (when Bonjour can't see the other Mac) in Macs & Sync and add the missing Mac by its name, such as other-mac.local, or its IP address.

When two Macs change the same thing

Each arrangement and each workspace syncs as a whole. If two Macs change the same one before they've synced, the most recent change wins and replaces the other. The two versions aren't merged. Deleting an arrangement or workspace removes it on every Mac.

Changes you make while another Mac is off or out of reach are sent when they connect again.

Keep every Mac on the same version

Macs & Sync shows the app and macOS version each other Mac runs. If the apps differ, it tells you which one to update, for example: "Studio runs an older version than this Mac (0.3.1). Update it there." License and updates explains how to update.

Wake your other Macs

On the Universal Control page, When this Mac wakes or is unlocked, wake my other Macs too is on by default. When you wake or unlock this Mac, your other Macs' displays turn on as well. You can also click Wake Other Mac Now. While another Mac's screens are asleep, Wake Other Mac appears in the menu bar.

If another Mac is fully asleep, the app sends it a Wake-on-LAN request instead. That needs Wake for network access turned on in that Mac's settings: see Apple's Set sleep and wake settings for your Mac. Whether it wakes also depends on the Mac and your network, so it isn't guaranteed. Compatibility lists the conditions.