Capslock goes native

Fri, 06 Nov 2026 00:00:00 +0000

For years Capslock was a configuration file. You installed Karabiner-Elements, imported a set of rules, and Caps Lock became Escape on a tap and a Hyper key on a hold. With Command, Option, Control and Shift it reached sixteen planes of shortcuts for the cursor, editing, windows, apps and the mouse.

That worked, and it kept two costs. Karabiner-Elements had to be installed, with its driver and its permissions, just to change one key. And the layout was a JSON file: to change a binding you edited that file, and to learn the layout you kept a picture of the keyboard open.

How Capslock works: F18, an event tap, and a mapping it gives back

Fri, 06 Nov 2026 00:00:00 +0000

Caps Lock sits in the best spot on the keyboard and does the least useful job. Capslock gives it a new one: tap it for Escape, hold it for Hyper, and combine it with the four modifiers to reach sixteen control planes. This post explains how a native app does that on macOS without a kernel extension, a driver, or a privileged helper.

Caps Lock is not a modifier

macOS does not report Caps Lock as a key that goes down and comes back up. It reports a lock state that flips, and it adds a short delay so that brushing the key does not toggle it. That is fine for typing capitals and useless for a modifier that must be held.

Posts on Capslock

Capslock goes native

How Capslock works: F18, an event tap, and a mapping it gives back

Caps Lock is not a modifier