Compare the Top Free Real-Time Operating Systems (RTOS) as of October 2025

What are Free Real-Time Operating Systems (RTOS)?

A real-time operating system (RTOS) is a specialized OS designed to process data and execute tasks within strict timing constraints. Unlike general-purpose operating systems, RTOS platforms prioritize predictability and determinism, ensuring tasks are completed within guaranteed time frames. They are widely used in embedded systems, robotics, aerospace, automotive electronics, medical devices, and industrial automation where delays could compromise safety or functionality. RTOS platforms often provide lightweight kernels, task scheduling, inter-process communication, and resource management optimized for reliability and low latency. By enabling consistent, time-critical performance, RTOS software ensures that mission-critical applications run smoothly under real-world conditions. Compare and read user reviews of the best Free Real-Time Operating Systems (RTOS) currently available using the table below. This list is updated regularly.

  • 1
    FreeRTOS

    FreeRTOS

    FreeRTOS

    Developed in partnership with the world’s leading chip companies over a 15-year period, and now downloaded every 170 seconds, FreeRTOS is a market-leading real-time operating system (RTOS) for microcontrollers and small microprocessors. Distributed freely under the MIT open source license, FreeRTOS includes a kernel and a growing set of IoT libraries suitable for use across all industry sectors. FreeRTOS is built with an emphasis on reliability and ease of use. With proven robustness, tiny footprint, and wide device support, the FreeRTOS kernel is trusted by world-leading companies as the de facto standard for microcontrollers and small microprocessors. With detailed pre-configured demos and Internet of Things (IoT) reference integrations, there is no need to determine how to setup a project. Quickly download, compile, and get to market faster. Our partner ecosystem provides a breadth of options including community contributions and professional support.
  • 2
    Mbed OS
    Arm Mbed OS is a free, open-source IoT operating system that includes all the necessary features to develop IoT products. The OS includes everything you need to develop smart, connected products on Arm Cortex-M based hardware, including machine learning capabilities, security, connectivity stacks, an RTOS kernel and drivers for sensors and I/O devices. Arm Mbed OS is designed for the Internet of Things. It is integrated with connectivity, machine learning, networking, and security stacks and is supported with software libraries, development hardware, tutorials and examples. From hardware to the cloud, Mbed OS supports more than 70 silicon, module, cloud, and OEM partners, optimizing your developer choice. By using the Mbed OS API, your application code can remain clean, portable, and simple, while taking advantage of security, communications and machine learning. The integrated solution reduces development cost, time, and risk.
  • 3
    RT-Thread

    RT-Thread

    RT-Thread

    Welcome to the RT-Thread initiative on SourceForge! RT-Thread is a community-led, open-source Real-Time Operating System. It boasts an extensive feature set, compatibility with over 600 ready-to-use software packages and a broad spectrum of components, and supports all mainstream chip architectures. It also includes a proprietary IDE, the RT-Thread Studio, to assist engineers in quickly embarking on embedded and IoT development. Designed with scalability in mind, RT-Thread is a flexible option for various IoT applications, thanks to its Nano version tailored for resource-limited applications. We invite you to join us on this thrilling journey and help shape the future of IoT and RTOS!
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