Open Source Real-Time Operating Systems

ChibiOS is a modular, high-performance development environment for embedded systems, featuring a dual-kernel architecture with the full-featured RT kernel and the ultra-compact NIL kernel. It provides a comprehensive Hardware Abstraction Layer (HAL), a Virtual File System (VFS), and advanced sandboxing capabilities, making it highly suitable for functional safety and multicore ARM Cortex-M applications.

Apache NuttX is a highly scalable, standards-compliant real-time operating system (RTOS) designed for deeply embedded environments ranging from 8-bit to 64-bit architectures. It distinguishes itself by strictly adhering to POSIX and ANSI standards, providing a familiar Unix-like programming interface while maintaining a minimal footprint and modular architecture.

RT-Thread is a modular, object-oriented real-time operating system (RTOS) designed for both resource-constrained microcontrollers and high-performance IoT devices. It provides a scalable architecture ranging from a 3KB footprint kernel to a comprehensive IoT OS featuring a vast ecosystem of over 450 software packages and standardized interfaces like POSIX and CMSIS.

TizenRT is a lightweight, RTOS-based platform designed for low-end IoT devices with limited resources, typically equipped with ARM Cortex-M/R processors and less than 2MB of RAM. It extends the NuttX kernel with a comprehensive ecosystem including Linux-style development environments, advanced networking stacks, and support for high-level languages like JavaScript to bridge the gap between RTOS efficiency and Linux-like developer experience.

FreeRTOS is a market-leading real-time operating system kernel designed for microcontrollers and small microprocessors, featuring a small memory footprint and fast execution times. It provides a comprehensive ecosystem of libraries for IoT connectivity, security, and over-the-air updates, supporting over 40 processor architectures including ARM and RISC-V.

RIOT is a modular, open-source real-time operating system specifically engineered for the Internet of Things (IoT), supporting a wide range of 8-bit, 16-bit, and 32-bit microcontrollers. It features a micro-kernel architecture with a preemptive, tickless scheduler and provides a uniform API with partial POSIX compliance to simplify cross-platform development and code reuse.

Embox is a highly modular and configurable real-time operating system designed to execute Linux-compatible software on resource-constrained embedded systems and microcontrollers. It provides a POSIX-compliant environment, allowing developers to port complex desktop-grade libraries and applications like Qt, OpenCV, and PJSIP to platforms with limited RAM and ROM.

Apache Mynewt OS is a real-time, modular operating system for connected IoT devices that need to operate for long periods of time under power, memory, and storage constraints. It provides a complete environment for prototyping, developing, and managing em