Open Source Real-Time Operating Systems

The Zephyr™ Project is a scalable, real-time operating system (RTOS) supporting multiple hardware architectures, optimized for resource constrained devices, and built with security in mind. This Linux Foundation hosted project embraces open source development values and governance on its mission to unite leaders from across the industry to produce a best-in-breed solution.

RT-Thread is an open source real-time operating system for embedded devices from China. RT-Thread RTOS is a scalable real-time operating system: a tiny kernel for ARM Cortex-M0, Cortex-M3/4, or a full feature system in ARM Cortex-A8, ARM Cortex-A9 DualCor

TencentOS tiny is a real-time operating system developed by Tencent for the Internet of Things. It features low power consumption, low resource consumption, modularity, security and reliability, and can effectively improve the development efficiency of IoT terminal products.

Tock is a secure embedded operating system designed for Cortex-M and RISC-V microcontrollers. It focuses on providing isolation between components, ensuring safety and security. The Tock kernel and its extensions, known as capsules, are written in Rust, a systems programming language known for its memory safety and type safety features. Tock supports multiple, independent untrusted processes, which can be written in any language. The system is designed to be preemptive, using a round-robin scheduling policy, and offers a microkernel architecture.

FreeRTOS is a market leading RTOS from Amazon Web Services that supports more than 35 architectures. It is distributed under the MIT license.

RIOT is a real-time multi-threading operating system that supports a range of devices that are typically found in the Internet of Things (IoT): 8-bit, 16-bit and 32-bit microcontrollers.

Huawei LiteOS is a lightweight open-source IoT OS and a smart hardware development platform. It simplifies IoT device development and device connectivity, makes services smarter, delivers superb user experience, and provides better data protection. Huawei LiteOS is designed for smart homes, wearables, IoV, and intelligent manufacturing applications.

The world's first operating-system kernel with an end-to-end proof of implementation correctness and security enforcement is available as open source.

mbed OS is an open-source embedded operating system designed specifically for the "things" in the Internet of Things (IoT). It includes all the features you need to develop a connected product based on an ARM Cortex-M microcontroller.

AliOS Things is designed for low power, resource constrained MCU, connectivity SoC, greatly suitable for IoT devices. AliOS Things is not just a RTOS, it contains full stack of software components and tools for building IoT devices.

Contiki is an open source operating system for the Internet of Things. Contiki connects tiny low-cost, low-power microcontrollers to the Internet.

Hubris is an open-source operating system designed for deeply-embedded computer systems. Developed by Oxide Computer Company, it's an all-Rust system that focuses on security, robustness, and efficiency for embedded systems.

NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 32-bit microcontroller environments, the primary governing standards in NuttX are Posix and ANSI standards.

This advanced real-time operating system (RTOS) is designed specifically for deeply embedded applications. Among the multiple benefits it provides are advanced scheduling facilities, message passing, interrupt management, and messaging services. Eclipse ThreadX has many advanced features, including picokernel architecture, preemption threshold, event chaining, and a rich set of system services.

Mongoose OS - an open source Operating System for Internet of Things. Supported microcontrollers: ESP32, ESP8266, CC3220, CC3200, STM32F4. Amazon AWS IoT & Google IoT Core integrated. Code in C or JavaScript.

RIOT, the hardware accelerated Rust RTOS. A concurrency framework for building real-time systems.

TinyOS is an open source, BSD-licensed operating system designed for low-power wireless devices, such as those used in sensor networks, ubiquitous computing, personal area networks, smart buildings, and smart meters.

CMSIS is a set of tools, APIs, frameworks, and workflows designed to simplify software re-use, reduce the learning curve for microcontroller developers, and accelerate project build and debug processes. It was initiated as a vendor-independent hardware abstraction layer for Arm® Cortex®-M based processors and later expanded to support entry-level Arm Cortex-A based processors. CMSIS aims to provide a consistent approach to interface with peripherals, real-time operating systems, and middleware components.

Contiki-NG is an operating system for resource-constrained devices in the Internet of Things. Contiki-NG contains an RFC-compliant, low-power IPv6 communication stack, enabling Internet connectivity.

Embox is a configurable operating system kernel designed for resource constrained and embedded systems.

A lightweight Active Object implementation for real-time embedded systems.

µC/OS-III is a highly portable, ROMable, scalable, preemptive, real-time, deterministic, multitasking kernel for microprocessors, microcontrollers and DSPs.

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

ChibiOS is a complete development environment for embedded applications including RTOS, an HAL, peripheral drivers, support files and a development environment.

F9 microkernel is a microkernel-based (L4-style) kernel to support running real-time and time-sharing applications (for example, wireless communications) for ARM Cortex-M series microprocessors with efficiency (performance + power consumption) and security (memory protection + isolated execution) in mind.

Trampoline is a static RTOS for small embedded systems. Its API is aligned with OSEK/VDX OS and AUTOSAR OS 4.2 standards.

TizenRT is a lightweight RTOS (Real-Time Operating System) designed to support low-end IoT devices. It aims to extend the Tizen platform device coverage to devices like home appliances without display and wearable bands with a small LCD. These devices are typically equipped with Cortex-M/R processors with MPU, less than 2 MB RAM, and less than 16 MB Flash.

RTEMS is an open source RTOS that supports open standard application programming interfaces such as POSIX. It is used in space flight, medical, networking and many more embedded devices.

μC/OS-II is a portable, ROMable, scalable, preemptive, real-time deterministic multitasking kernel for microprocessors, microcontrollers and DSPs.

Drone is an Embedded Operating System for writing real-time applications in Rust.

distortos is an object-oriented C++ RTOS for microcontrollers.

Atomthreads is a free, lightweight, portable, real-time scheduler for embedded systems.

QuarkTS is a simple non-Preemtive Real-Time OS with a quasi-static scheduler for embedded multi-tasking applications.

TNeo is a well-formed and carefully tested preemptive real-time kernel for 16- and 32-bits MCUs. It is compact and fast.

Frosted is an acronym that means "Free Operating Systems for Tiny Embedded Devices". The goal of this project is to provide a Free (as in Freedom) kernel for embedded systems, which exposes a POSIX-compliant system call API.

Erika Enterprise is the first open-source Free RTOS that has been certified OSEK/VDX compliant!.

scmRTOS is tiny Real-Time Preemptive Operating System intended for use with Single-Chip Microcontrollers. scmRTOS is capable to run on tiny uCs with as small amount of RAM as 512 bytes. The RTOS is written on C++ and supports various platforms.

Free, extremely simple and amazingly tiny real-time operating system (RTOS) designed for deeply embedded applications. Target: ARM Cortex-M, STM8. It was inspired by the concept of a state machine.

The eChronos RTOS is a real-time operating system (RTOS) originally developed by NICTA and Breakaway Consulting Pty. Ltd. It is intended for tightly resource-constrained devices without memory protection.

A Reliable Real-Time Operating System & Application Framework.

BeRTOS is a real time open source operating system supplied with drivers and libraries designed for the rapid development of embedded software.

Phoenix-RTOS is an open-source, microkernel-based, realtime operating system for resource constrained devices.

StratifyOS is a powerful embedded RTOS for the ARM Cortex M microcontrollers.

BRTOS is a lightweight preemptive real time operating system designed for low end microcontrollers.

DuinOS is a small multithreading real time operating system (RTOS), based on the FreeRTOS kernel, for Arduino compatible boards.

MOE is an event-driven scheduler system for 8/16/32-bit MCUs. MOE means "Minds Of Embedded system".

Free, simple and tiny cooperative operating system (OS) designed for deeply embedded applications.

LibreRTOS is a portable single-stack Real Time Operating System. All tasks share the same stack, allowing a large number or tasks to be created even on architectures with low RAM, such as ATmega328P (2kB).

The hyperC OS is a real time-operating system (RTOS) designed for various IoT applications. All the designs are aimed at the optimization of ARM Cortex CPUs.

HuskEOS is a real-time operating system (RTOS) designed for embedded systems. It offers a priority-based preemptive scheduler and boasts impressive performance metrics, such as achieving 50,000 context switches per second on a Cortex-M4 configured at 16MHz.

RA3 RTOS is a lightweight, open-source real-time operating system specifically designed for embedded systems.

The TOPPERS/ATK (Automotive Kernel) is a real-time operating system for automotive system control publicly released by the TOPPERS project.

Femto OS: RTOS for small MCU's like AVR.

Mark3 is a sophisticated, modern RTOS and application development platform, targeted towards a growing list of today's most compelling embedded devices.

Nut/OS is an intentionally simple RTOS for the ATmega128, which provides a minimum of services to run Nut/Net, the TCP/IP stack.

Prex is an open source, royalty-free, real-time operating system for embedded systems. It is designed and implemented for resource-constrained systems that require predictable timing behavior. The highly portable code of Prex is written in 100% ANSI C bas

RTAI is the RealTime Application Interface for Linux - which lets you write applications with strict timing constraints for your favourite operating system. The RTAI distribution includes RTAI-Lab, a tool chain to convert block diagrams into RTAI executab

uSmartX is a non-preemptive, multitasking, priority based RTOS.

Xenomai is a real-time development framework cooperating with the Linux kernel, in order to provide a pervasive, interface-agnostic, hard real-time support to user-space applications, seamlessly integrated into the GNU/Linux environment.