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.

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.

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.

Hubris is a memory-isolated, task-based RTOS written in Rust, specifically designed for deeply-embedded microcontrollers with high reliability requirements. It eliminates dynamic resource allocation and runtime task creation to minimize attack surfaces and ensure deterministic behavior in critical systems.

Mongoose OS is a modular IoT firmware development framework designed for microcontrollers, enabling rapid development in both C/C++ and JavaScript. It provides a comprehensive environment for connected devices with built-in support for secure OTA updates, remote management via a robust RPC mechanism, and native integration with major cloud providers like AWS IoT and Google IoT Core.

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.

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.

Zephyr is a scalable, security-focused real-time operating system (RTOS) designed for resource-constrained devices across multiple hardware architectures. It features a modular, small-footprint kernel with an extensive suite of subsystems, including a native networking stack, comprehensive Bluetooth Low Energy support, and a robust device driver model.