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Swap or remap modifier keys (Ctrl, Command, Alt Gr) in Synergy 1 and Synergy 3

Updated

Written for Synergy 3 (v3.7.2) and Synergy 1 (v1.21.4), checked 3 October 2026.

To change what a modifier key does on one of your computers, remap it for the computer whose keys you want to change. For example, when sharing a Windows keyboard with a Mac, using the hotkey for copy, Command+C, can be tricky because the Windows key is in a different place than the Command key on a Mac; swapping Ctrl and Super on the Mac fixes that.

A remap changes the keys on that computer only, and only while another computer controls it. Remapping the primary computer (the server) has no effect unless it becomes a secondary computer (a client).

Synergy 3

  1. Open Synergy 3.
  2. Go to Screen layout.
  3. Click the ⋯ menu on the computer whose keys you want to change (for example the Mac).
  4. Click Computer preferences.
  5. Go to the Modifier keys tab.
  6. Set Super to Ctrl.
  7. Set Ctrl to Super.
  8. Click Save.

Each key can become Shift, Ctrl, Alt or Super, and each can be used only once: until you've set both keys of a swap, Synergy 3 shows The right column has duplicates. To remap to Meta as well, first switch on Enable meta key (not the start or command key) in Miscellaneous.

Synergy 1

  1. Open Synergy 1 on your server computer.
  2. Click Configure Server.
  3. On the Computers tab, double-click the computer whose keys you want to change (for example the Mac). The Computer settings window opens.
  4. Under Modifier Keys, set Super to Ctrl.
  5. Set Ctrl to Super.
  6. Click Save.
  7. Click OK to close Server Configuration. If Synergy 1 is running, it restarts with the new configuration.

In Synergy 1, Shift, Ctrl, Alt, Alt Gr, Meta and Super can each be set to any of those keys or to None.

Fix Alt Gr on another computer

If Alt Gr (the right-hand Alt key used to type accented and other alternate characters) does nothing on the computer you control, or acts as Alt or left Alt, try the remap below. This is a known issue in both Synergy 1 and Synergy 3 that we're working on.

Synergy 3

  1. Go to Keyboard & mouse.
  2. Switch Alt Gr for PC keyboards only off (or on, if it was off).

It's on by default, and while it's on, Alt Gr on a PC keyboard acts as Alt on your other computers. The setting is explained in: Keyboard and mouse settings in Synergy 3

Synergy 1

  1. Open Synergy 1 on your server computer.
  2. Click Configure Server.
  3. Double-click the computer where Alt Gr misbehaves.
  4. Under Modifier Keys, set Alt to Alt Gr.
  5. Click Save.
  6. Click OK.

If that doesn't help, set Alt back to Alt and set Alt Gr to Alt instead. In a text config file, the same remaps are alt = altgr and altgr = alt under the client in section: screens. For the file format, see: Creating and using text config files

If the right Alt key on a Linux server sends Alt Gr when your client expects right Alt, see: Keycode or key combinations don’t match

Check your changes

Once you have made the changes it can be helpful to open up the on-screen keyboard to see how the changes you have made are reflected on the client. On Windows, it's called the On-Screen Keyboard, and on macOS, it's called the Accessibility Keyboard.

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