Karabiner-Elements is a system-level utility designed for advanced keyboard and mouse customization. It functions as a background service that intercepts raw hardware input signals at the driver level, allowing for the transformation of key presses and pointer movements before they reach the operating system. By utilizing virtual input device emulation, the software re-injects modified events into the system stream, enabling complex remapping, macro execution, and hardware-specific control.
The project distinguishes itself through a sophisticated state-based logic engine that enables context-aware behavior. Users can define rules that trigger based on the currently active application, specific hardware devices, or persistent system variables. This includes support for arithmetic expression evaluation and timing-based logic, such as executing different commands depending on whether a key is tapped, held, or pressed in rapid succession. The configuration is managed through a structured text-based schema, which can be validated and automated via command-line tools.
Beyond basic remapping, the software provides comprehensive control over peripheral hardware, including the ability to disable built-in keyboards when external devices are connected and to transform mouse motion into scroll events. It also features robust monitoring tools for inspecting raw device signals and system logs to facilitate troubleshooting. The application maintains functionality within secure environments, such as password prompts, by managing the necessary system-level permissions and extensions required for deep input integration.
