1.zephyrproject-rtos / zephyr Primary Git Repository for the Zephyr Project. Zephyr is a new generation, scalable, optimized, secure RTOS for multiple hardware architectures. rtos iot embedded real-time mcu microcontroller +6 more C APACHE-2.0 17K total 10K forks +64 stars from 16,997 · score 4.17
2.FreeRTOS / FreeRTOS 'Classic' FreeRTOS distribution. Started as Git clone of FreeRTOS SourceForge SVN repo. Submodules the kernel. C MIT 8K total 2.1K forks +24 stars from 7,954 · score 3.22
3.RT-Thread / rt-thread RT-Thread is an open source IoT Real-Time Operating System (RTOS). https://rt-thread.github.io/rt-thread/ embedded-systems kernel iot rtos arm cortex-m +7 more C APACHE-2.0 12K total 5.5K forks +21 stars from 12,326 · score 3.09
4.tock / tock A secure embedded operating system for microcontrollers embedded operating-system rust cortex-m kernel tock +6 more Rust Other license 6.5K total 868 forks +9 stars from 6,486 · score 2.30
5.RIOT-OS / RIOT RIOT - The friendly OS for IoT c iot os internetofthings microcontrollers rtos +4 more C LGPL-2.1 5.8K total 2.1K forks +8 stars from 5,833 · score 2.20
6.tinyos / tinyos-main Archived Main development repository for TinyOS (an OS for embedded, wireless devices). nesC No license 1.5K total 525 forks +1 stars from 1,501 · score 0.69