Officially supported microcontrollers

While most CircuitPython devices are great for hand wired keyboards, most keyboards are designed to accept a Pro Micro. The boards listed below either are, or can be adapted to that pinout to use common keyboards already on the market.

nice!nano

Features include - Pro Micro pinout - Both USB HID and Bluetooth support - Can do Bluetooth split keyboards with no wires at all - Has battery support including charging

Downsides - $25 USD per microcontroller at most retailers - Not enough space to run KMK without compiling

Pre-compiling KMK for nice!nano (or any other microcontroller with limited flash)

As the nice!nano has limited flash memory you'll need to use a compiled KMK.

ItsyBitsy M4 Express

Features include - Affordable at $15 USD - Can run most features of KMK including RGB

Downsides - Needs to be adapted to work with Pro Micro pinout keyboards. You can find a tutorial and files for such an adapter in our GitHub repository under /hardware

RP2040

Features include - Very affordable - Very powerful for the price

Downsides - Little support for keyboard kits

Adafruit ItsyBitsy nRF52840 Express

Features include - Both USB HID and Bluetooth support - More affordable than the nice!nano at only $18

Downsides - Needs to be adapted to work with Pro Micro pinout keyboards. You can find a tutorial and files for such an adapter in our GitHub repository under /hardware - No battery support without addon board like this one by adafruit

Other microcontrollers

What you'll need to have at minimum - CircuitPython - 256KB of flash storage - HID over USB and/or Bluetooth.

Please keep in mind that KMK relies on CircuitPython's ability to use Bluetooth Low Energy with any given controller.