| FreeRTOS | MIT | MSP430 ARM AVR ColdFire PIC x86 | FreeRTOS is a popular real-time operating system for embedded devices, being ported to 31 microcontrollers. It is distributed under the GPL with an optional exception. | V10.0.1 | Code | 2017-12-26 |
| RT-Thread | Modified GPL v2 | ARM x86 MIPS PowerPC RISC-V Andes | 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 | v3.0.2 | GitHub | 2017-12-31 |
| Contiki OS | BSD | MSP430 ARM AVR 8051 | Contiki is an open source operating system for the Internet of Things. Contiki connects tiny low-cost, low-power microcontrollers to the Internet. | 3.0 | GitHub | 2017-10-11 |
| mbed OS | Apache License | ARM | 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. | 5.1 | GitHub | 2016-09-17 |
| ChibiOS/RT | Modified GPL | MSP430 AVR | ChibiOS is a complete development environment for embedded applications including RTOS, an HAL, peripheral drivers, support files and a development environment. | 17.6.2 | Code | 2017-10-03 |
| NuttX | BSD | ARM AVR 8051 x86 | 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. | 7.23 | Code | 2018-01-01 |
| RIOT | LGPLv2.1 | MSP430 AVR | 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. | 2018.01 | GitHub | 2018-01-31 |
| Mongoose OS | GPL v2 | ARM | 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. | 1.25 | GitHub | 2018-01-25 |
| RTEMS | GPL | ARM x86 MIPS PowerPC m68k | 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. | 4.11 | Code | 2016-09-23 |
| Apache Mynewt | Apache License | ARM | 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 | pre_sterly_refactor | GitHub | 2016-09-21 |
| Xenomai | GPL | ARM x86 PowerPC | 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. | v3.0.3 | Code | 2016-09-10 |
| Atomthreads | BSD | AVR | Atomthreads is a free, lightweight, portable, real-time scheduler for embedded systems. | release1.3 | GitHub | 2017-08-27 |
| StratifyOS | GPL | ARM | StratifyOS is a powerful embedded RTOS for the ARM Cortex M microcontrollers. | v3.3.0 | GitHub | 2018-01-12 |
| distortos | Mozilla Public License Version 2.0 | ARM | Distortos is an advanced RTOS written in C++11. | v0.5.0 | GitHub | 2017-09-14 |
| Zephyr | Apache License | ARM x86 | 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. | zephyr-v1.10.0 | GitHub | 2017-12-08 |
| StateOS | GPL v3 | ARM | Free, extremely simple and amazingly tiny real-time operating system (RTOS) designed for deeply embedded applications. Target: ARM Cortex-M family. It was inspired by the concept of a state machine. | v5.6 | GitHub | 2018-01-24 |
| F9 Microkernel | BSD | ARM | 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. |
| GitHub | 2017-02-02 |
| BRTOS | MIT | MSP430 AVR ColdFire PIC | BRTOS is a lightweight preemptive real time operating system designed for low end microcontrollers. |
| GitHub | 2017-09-17 |
| BeRTOS | Modified GPL | AVR x86 PowerPC x86_64 | BeRTOS is a real time open source operating system supplied with drivers and libraries designed for the rapid development of embedded software. |
| GitHub | 2017-01-23 |
| Erika Enterprise | Modified GPL | MSP430 ARM AVR | Erika Enterprise is the first open-source Free RTOS that has been certified OSEK/VDX compliant!. | 2.7.0 | Code | 2016-06-15 |
| BitThunder | GPL v2 | ARM | A Reliable Real-Time Operating System & Application Framework. | stable-0.9.2 | GitHub | 2017-01-25 |
| TI-RTOS Kernel | Other |
| TI-RTOS Kernel (formerly known as SYS/BIOS | v3.00.00 |
| 2016-07-09 |
| TNeo | Other | ARM | TNeo is a well-formed and carefully tested preemptive real-time kernel for 16- and 32-bits MCUs. It is compact and fast. | v1.08 | GitHub | 2017-02-25 |
| LibreRTOS | Apache License | AVR | 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). | dev-master | GitHub | 2017-11-15 |
| IntrOS | GPL v3 | ARM | Free, simple and tiny cooperative operating system (OS) designed for deeply embedded applications. | v3.6 | GitHub | 2018-01-24 |
| embox | Other | MSP430 ARM MIPS PowerPC | Embox is a configurable operating system kernel designed for resource constrained and embedded systems. | v0.3.20 | GitHub | 2017-12-31 |
| uKOS | GPL v3 | ARM | uKOS is a multi-tasking OS suitable for small embedded μController systems. It is based on a preventive multitasking scheduler. | 4.0.0 |
| 2017-04-26 |
| seL4 | Other | ARM | The world's first operating-system kernel with an end-to-end proof of implementation correctness and security enforcement is available as open source. | 8.0.0 | GitHub | 2018-01-17 |
| Trampoline | GPL v2 | ARM AVR PowerPC | Trampoline is a static RTOS for small embedded systems. Its API is aligned with OSEK/VDX OS and AUTOSAR OS 4.2 standards. | dev-master | GitHub | 2017-12-07 |
| eChronos | Other | PowerPC | 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. | v2.3.0 | GitHub | 2018-01-18 |
| AliOS Things | Apache License | ARM | 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. | v1.1.2 | GitHub | 2017-12-17 |
| LiteOS | BSD | ARM | 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. | v1.1.2 | GitHub | 2018-02-06 |
| TizenRT | Apache License 2.0 | ARM | TizenRT is a lightweight RTOS-based platform to support low-end IoT devices | 1.1_Public_Release | GitHub | 2018-02-11 |
| MOE | MIT | ARM | MOE is an event-driven scheduler system for 8/16/32-bit MCUs. MOE means "Minds Of Embedded system". | V0.1.6 | GitHub | 2018-03-20 |
