Open-source firmware

Open-source firmware is firmware that is published under an open-source license. It can be contrasted with proprietary firmware, which is published under a proprietary license or EULA.

Examples

OpenWrt
DD-WRT
coreboot
SeaBIOS
LinuxBoot
Libreboot
Marlin, Arduino-based firmware for 3D printers
PinePhone LTE modem
Rockbox, a replacement firmware for various digital audio players
QMK
U-Boot