Making Caps Lock do something useful on the Mac

by Jesper Rasmussen

Update: PCKeyBoardHack and KeyRemap4MacBook are now called Seil and Karabiner - the screenshots still reflect the old names though.

Let's face it. Caps Lock is useless. Unless you're in the habit of writing all-caps e-mails, you'll probably only use Caps Lock when hitting it by accident.

For the last couple of years, I've made a habit out of disabling my Caps Lock, or changing it to do something better. The key itself is useful, its size make it easy to hit, and it's easily accessible.

What you'll need

On the Mac, there's a few handy apps that allow you to modify your key layout.

Seil

Seil allows you to change the keycode your keys are firing. This will be useful later on. To do so, either follow the simple guide on the website or do the following:

  1. Download and install Seil
  2. Start up the application
  3. Enable "Change Caps Lock" as shown below, and set it to keycode 110. Keycode 110 is called PC application key on a PC keyboard, but is not used on a Mac. So, for now your Caps Lock key does nothing. So far so good.

Also, Mac OS per default limits the responsiveness of Caps Lock. Which is nice, as it hinders a lot of accidental Caps Lock use, but if we want to actually use Caps Lock for somthing, we need to make it faster. This is done by entering System Preferences -> "Keyboard" -> "Modifier Keys", and setting Caps Lock to "No Action" as shown below.

Mapping the key with Karabiner

Next up, we want the key to do something else. As you remember, I remapped it to PC Application Key, but I really want it to fire a key combination, like Option + Space (Which, in my example is what I use for OmniFocus - Per default this key combination triggers Spotlight).

So, onto the scene comes Karabiner, which allows for keycodes like PC Application Key, to fire a key combination. To map the PC Application Key (i.e. Caps Lock) to fire Option + Space, do the following:

  1. Download and install Karabiner.
  2. Start it up
  3. You'll notice a looong list of keys to remap. However, you can search this list as shown below, and only show the mapping options for PC Application Key for instance.
  4. As you'll notice below, it's possible to map the key to a lot of different options, for instance "Application Key to Option_L+Space", which in this case fires - Yep, you guessed it: Option + Space.

When this is done, your Caps Lock should now fire the wanted key combination, and you can use Caps Lock for something useful, like triggering Quick Entry in OmniFocus, triggering Alfred etc.