Keychange

Keychange is a macOS menu bar app that assigns a system input source to each physical keyboard and switches to it automatically when you start typing on that device.

macOS can change input sources per app or by keyboard shortcut, but not per keyboard, so people using keyboards with different layouts have to switch by hand each time they move between them. Keychange removes that step. Keyboards are identified by their HID device, and mappings are kept when a keyboard is unplugged and reconnected.

It can switch before the key press is delivered, so even the first character after a switch comes out right (opt-in), and it has strategies for what to do when the input source is changed by something else.

Keychange requires Input Monitoring access to identify which device a key press came from. Accessibility access is needed only for the optional before-key-press mode. It stores no keystroke data and makes no network requests other than checking for updates.