RIOT

Zephyr

zephyrproject-rtos/zephyr

TrendingPopular

Linux Foundation RTOS with devicetree, Kconfig and hundreds of boards; the fastest-growing vendor-neutral MCU OS.

FreeRTOS

FreeRTOS/FreeRTOS-Kernel

Popular

Tiny, MIT-licensed real-time kernel stewarded by AWS; the most widely deployed RTOS on microcontrollers.

Yocto Project

yoctoproject.org

Popular

BitBake and OpenEmbedded build system for custom embedded Linux distributions; the industry standard for products.

Buildroot

buildroot/buildroot

Simple Makefile and Kconfig tool that generates small embedded Linux root filesystems, kernels and toolchains.

Apache NuttX

apache/nuttx

POSIX-compliant RTOS that scales from 8-bit to 64-bit MCUs; used by PX4 drones and Xiaomi's Vela OS.

Eclipse ThreadX

eclipse-threadx/threadx

Former Azure RTOS, now MIT-licensed at Eclipse; safety-certified kernel with NetX, FileX and GUIX add-ons.

RT-Thread

RT-Thread/rt-thread

Open-source RTOS with a rich component and package ecosystem; very widely used across China's IoT industry.

OpenWrt

openwrt/openwrt

Linux distribution for routers and network appliances with a writable filesystem and package manager.

Mbed OS

ARMmbed/mbed-os

Legacy

Arm's IoT RTOS and platform, end-of-life since July 2026; migrate to Zephyr or the community Mbed CE fork.