Hyperkey

Hyperkey lets you repurpose an unused key—most commonly Caps Lock—into a “Hyper” modifier that combines Control, Option, Command, and Shift. Once configured, the new modifier can be used in any application to create custom keyboard shortcuts, giving you an additional, always‑available combination without altering existing key behavior. The app runs as a lightweight background service and works alongside other macOS utilities such as Rectangle.

The utility is aimed at power users and developers who rely on extensive shortcut schemes, as well as anyone looking to make better use of rarely used keys. It integrates with macOS’s keyboard handling, allowing the Hyper key to be recognized by most apps, though secure password fields block third‑party key monitoring for privacy reasons. Hyperkey is distributed as free‑tier software and is considered stable for everyday use.