Synergy 3

v3.9.1 (October 29, 2026)

Security

• Third-party components: The node-forge library, which Synergy 3 uses to create its own certificate, had published security advisories, including CVE-2026-85393, and has been updated to clear them.

Features

• If the other computers in your screen layout stop answering while one with your serial key is on the network in another setup, Synergy 3 now tells you and offers a button to join that setup. One click and your computers are back together, with no need to reset them all and start again. Add computers also marks such a computer "In another setup", with a "Join setup" button.
• Your screen layout now shows a short match code beside "This computer's details". Every computer using your serial key shows the same code, so you can tell at a glance whether they all have the same key.

Enhancements

• The tutorial now walks you through setup a step at a time, from matching each computer's shape to choosing your primary computer and moving your mouse across. Bring it back any time with "Show tutorial" on the General page.
• Add computers now shows the computers Synergy 3 finds on your network and lets you type an address on the same page, so adding a computer works the same way whichever you use.
• If you remove a computer from your layout, it keeps its name and goes straight to Add computers, so you won't be asked to name it again.

Bug fixes

• If you set up two new computers on 3.9.0 and they could find each other but never connected, they will now. Adding a computer by its address works again.
• Reset all computers now gives you a clean start on every computer. Before, some could come back holding the old layout and a primary that no longer existed, and sharing never started on them.
• Making another computer primary no longer asks you to compare codes again. You compare codes once, when a computer joins.
• When you resize or move a screen in your layout, it now follows your mouse instead of jumping back, and a burst of quick changes reconnects your computers once instead of once for each.

v3.9.0 (October 27, 2026)

Features

• A new computer now asks which setup to join. After you name it, Synergy 3 lists the computers on your network that use the same serial key, and you can join one, start a new setup, or connect by address. Separate setups on one network that share a serial key no longer merge into one screen layout.
• Synergy 3 now finds a newer license when it starts, for example when a trial becomes a paid license, so you don't have to enter the new serial key. You can turn this off on the License page.
• The log now opens on a page of the main window instead of in a separate window.

Enhancements

• "Auto discover" is now "Discoverable", set on each computer, and decides only whether other computers can find this one.
• When a computer you removed from the screen layout keeps trying to connect, the server now says so and offers to add it back.
• Both computers now show the compare-codes prompt, including when only one of them had stopped trusting the other, so the codes can always be compared.
• Your license now has its own License page in the settings, showing the product, the license type, who it is registered to and the full serial key.

Bug fixes

Windows

• Removed the console windows that flashed up after installing and while Synergy 3 was running.

macOS

• Stopped a Mac client crashing about 10 seconds after it started, which sent the cursor back to the server every 10 seconds.
• The installer now recovers the background service when macOS stops starting it, instead of waiting on "Waiting to install background service..." forever.

All computers

• Corrected the server hanging, with its own keyboard and mouse dead, when a client stopped responding while the server was sending to it.
• Connections are no longer rejected for a serial key mismatch after a restart when both computers have the same serial key.
• Removed computers no longer appear in Manage computers or as hotkey targets, and editing one no longer shows an error.
• A connection rejected while the main window was closed no longer shows a "problem with the GUI back-end" error.
• The background service now waits for another running copy of itself to stop, instead of exiting for good and leaving the window waiting, and the window shows a spinner meanwhile.
• The sharing process now stops along with the background service, so the next start no longer reports a conflicting sharing process.