Karabiner Elements 15.0.0

Karabiner Elements (earlier was Karabiner, and even earlier was KeyRemap4MacBook) is powerful and stable keyboard customizer for macOS.

Simple Modifications: Map normal keys to arbitrary key functions
Complex Modifications: Map keys by complex rules. e.g., key to modifiers, modifiers+key to key, send key event if pressed alone, etc
Function Keys: Map function keys to arbitrary key functions
Devices: Apply modifications to specified keyboards only
Profiles: Support the creation of multiple profiles that the user can switch between
Modifier Flag Sync:Synchronize modifier flags across all connected keyboards
Secure Keyboard Entry Support:Work well on Secure Keyboard Entry environment such as a password prompt, terminal with Secure Keyboard Entry, etc

Version 15.0.0:

macOS 11 and macOS 12 are no longer supported. The background service management method has been changed to a new method compatible with macOS 13 and later. Therefore, permission needs to be granted for the background service to run.
The method to enable the Multitouch Extension has changed.

Important Notes

A unique random ID called karabiner_machine_identifier is now generated during installation. This ID is used for machine-specific settings and may be included in the karabiner.json file.

New Features

Improvements

Improved "{device} is ignored temporarily until {key_code} is pressed again" message for to make it more understandable. (Thanks to @adamnovak)
Added "Enable Karabiner Notification Window" configuration, which allows you to hide the notification window by turning off this setting. (Thanks to @jwodnicki)
Support al_consumer_control_configuration key, used as the Music key. (Thanks to @kambala-decapitator)
Improved behaviour when using the gamepad stick as a pointing device.
Improved to_if_alone behavior to use the modifier flags of the time the key is pressed, when sending events.
Added {"type": "unset"} option to set_variable.
Integrated karabiner_observer functions into karabiner_grabber, and then karabiner_observer has been removed. The number of background processes has been reduced, resolving performance issues caused by inter-process communication that were occurring in some environments.
A custom JSON formatter has been introduced to save JSON in a more compact format.
The process for saving the configuration file has been optimized so that settings that have not been changed from their default values are not included in karabiner.json.
Internal changes: Improved the interface of libkrbn to minimize the use of unsafe pointers in Swift.

macOS 11.0 or later
Apple Silicon or Intel Core processor