Karabiner-Elements is a keyboard customizer for macOS. It lets you remap keys and build advanced keyboard behaviors, from simple swaps to complete custom rule sets.

Key features:

Configure simple key mappings from a graphical interface.
Import predefined rules from the community, such as a diamond cursor, Emacs or Vi key bindings, mouse keys, and protection against an unintended Command-Q.
Write your own rules or modify existing ones from scratch.

The current version supports macOS 13 Ventura through macOS 27, on both Intel and Apple silicon Macs, and older versions are available back to OS X 10.9. Karabiner-Elements is open source and free to use; you can optionally support the developer through GitHub Sponsors or a $10 PayPal payment.