Apps similar to Omnikey include BetterTouchTool. It's paid, but Karabiner Elements and Trident are free. Other options are Multitouch. In total there are four Key Mapping Tools like Omnikey for Mac.
Customizes input devices on macOS by enabling gesture and button mapping, keyboard shortcut assignment, window snapping, automation, scripting, multi-device integration, and iOS app control. Features include touch bar, Apple Remote, and per-app profiles.
Germany
EU
Karabiner, previously called KeyRemap4MacBook, is a very powerful keyboard remapper for Mac OS X. In addition to simple key remapping, it has special remapping modes like Emacs-mode, SandS-mode (Space and Shift).
Japan
Easily add more multitouch gestures to macOS, and customize what the gestures do. Multitouch is the most elegant Mac app for utilizing the power of your Magic Trackpad and Magic Mouse.
United States
Remaps Mac trackpad's three-finger tap to middle click and three-finger horizontal swipe to app switching, offering instant adjacent app switching or app-switcher HUD scrubbing. Includes customizable gesture toggles, palm rejection, and sensitivity settings.
