Best Real-Time Operating Systems (RTOS) for Windows of 2025

Developed in collaboration with top chip manufacturers over a span of 15 years, FreeRTOS is now downloaded approximately every 170 seconds and stands as a top-tier real-time operating system (RTOS) tailored for microcontrollers and small microprocessors. Available at no cost under the MIT open source license, FreeRTOS encompasses a kernel along with an expanding collection of IoT libraries that cater to various industries. Prioritizing reliability and user-friendliness, FreeRTOS is renowned for its proven durability, minimal footprint, and extensive device compatibility, making it the go-to standard for microcontroller and small microprocessor applications among leading global enterprises. With a wealth of pre-configured demos and IoT reference integrations readily available, users can easily set up their projects without any hassle. This streamlined process allows for rapid downloading, compiling, and quicker market entry. Furthermore, the ecosystem of partners offers a diverse range of options, including both community-driven contributions and professional support, ensuring that users have access to the resources they need for success. As technology continues to evolve, FreeRTOS remains committed to adapting and enhancing its offerings to meet the ever-changing demands of the industry.

Arm Mbed OS is an open-source operating system tailored for IoT applications, providing all the essential tools for creating IoT devices. This robust OS is equipped to support smart and connected products built on Arm Cortex-M architecture, offering features such as machine learning, secure connectivity stacks, an RTOS kernel, and drivers for various sensors and I/O devices. Specifically designed for the Internet of Things, Arm Mbed OS integrates capabilities in connectivity, machine learning, networking, and security, complemented by a wealth of software libraries, development boards, tutorials, and practical examples. It fosters collaboration across a vast ecosystem, supporting over 70 partners in silicon, modules, cloud services, and OEMs, thereby enhancing choices for developers. By leveraging the Mbed OS API, developers can maintain clean, portable, and straightforward application code while benefiting from advanced security, communication, and machine learning functionalities. This cohesive solution ultimately streamlines the development process, significantly lowering costs, minimizing time investment, and reducing associated risks. Furthermore, Mbed OS empowers innovation, enabling developers to rapidly prototype and deploy IoT solutions with confidence.

RT-Thread, short for Real Time-Thread, is an embedded real-time multi-threaded operating system. It has been designed to support multi-tasking, allowing multiple tasks to run simultaneously. Although a processor core can only run one task at a time, RT-Thread executes every task quickly and switches between them rapidly according to priority, creating the illusion of simultaneous task execution. RT-Thread is mainly written in the C programming language, making it easy to understand and port. It applies object-oriented programming methods to real-time system design, resulting in elegant, structured, modular, and highly customizable code. The system comes in a few varieties. The NANO version is a minimal kernel that requires only 3KB of flash and 1.2KB of RAM. For resource-rich IoT devices, RT-Thread can use an online software package management tool, together with system configuration tools, to achieve an intuitive and rapid modular design.

The SCIOPTA architecture is meticulously crafted to ensure outstanding real-time performance while maintaining a compact size. Its internal data structures, memory management, interprocess communication, and time management are all finely tuned for efficiency. Functioning as a pre-emptive real-time kernel, SCIOPTA allows interrupts to be handled at any moment, even during kernel execution. This operating system relies on a message-based model, providing a robust array of system calls for effective resource management. With standardized processes and interprocess communication protocols, SCIOPTA promotes clear system designs that are both easy to implement and maintain. The well-defined messaging system allows processes to communicate seamlessly and enables the grouping of processes into modules, making SCIOPTA particularly advantageous for collaborative efforts in large projects. The streamlined design significantly accelerates time-to-market, enhancing overall project efficiency. Moreover, the direct message passing capability between processes facilitates not only interprocess communication but also synchronization, further optimizing system performance.

Deos™, developed by DDC-I, is a safety-critical real-time operating system (RTOS) that has been rigorously verified according to DO-178C/ED-12C Design Assurance Level A (DAL A) standards specifically for avionics applications. This RTOS supports ARINC 653 APEX and rate monotonic scheduling (RMS), and it is designed to meet the FACE Safety Base Profile requirements. Since its initial verification by Transport Canada in 1998, it has been a trusted solution in the aviation industry, with its certification allowing it to operate in tens of thousands of aircraft. Over the past two decades, Deos has adapted and evolved to incorporate new processors and features, demonstrating its flexibility and resilience. It has also undergone successful audits by a range of global certification authorities, including the FAA, ENAC, JAA, EASA, and CAAC, as well as by designated engineering representatives from various airframe and avionics suppliers, ensuring its continued compliance with industry standards. Its proven track record and ongoing development make it a pivotal component in modern aviation safety systems.

INTEGRITY employs hardware memory protection to effectively isolate and safeguard embedded applications. By utilizing secure partitions, it ensures that every task has the necessary resources to operate correctly while simultaneously shielding the operating system and user tasks from erroneous and harmful code, which encompasses threats like denial-of-service attacks, worms, and Trojan horses. To facilitate developers in expediting their product creation, Green Hills Software provides a comprehensive suite of middleware that has been integrated and validated for use with INTEGRITY, featuring options like FFS, FAT, NFS, and journaling file systems, alongside both IPv4 and IPv6 host and routing networking stacks, as well as a FIPS 140-2 certified Suite B embedded encryption library, among other tools. Notably, each middleware package has undergone pre-integration and rigorous testing to ensure it operates smoothly with INTEGRITY’s sophisticated RTOS features. Furthermore, Green Hills Software also presents tailored platforms for various industries, which encompass a fully integrated ecosystem that includes the INTEGRITY RTOS along with essential development tools, aiming to streamline the development process even further. This cohesive approach not only boosts efficiency but also enhances the overall security of embedded applications.

PikeOS is a separation kernel-based hypervisor that supports multiple partitions for many operating systems and applications. It allows you to create smart devices for the Internet-of-Things. PikeOS is the best choice for systems that require protection against Cyber-Security attack due to its separation kernel approach. It is widely used in millions of edge and IoT systems. However, it has also been deployed in critical communications infrastructures. PikeOS combines virtualization and real time with unique technologies that have never been seen before. It allows you to move multiple complex embedded circuit boards into one hardware. It is also able to handle new hardware concepts like Big-SoCs that have multiple heterogeneous cores. PikeOS can run on multiple architectures and support processors that have a memory management unit (MMU).

Ranging from basic embedded environmental sensors and LED wearables to advanced embedded controllers, smartwatches, and IoT wireless applications, this system incorporates configurable architecture-specific stack-overflow protection, kernel object and device driver permission tracking, and thread isolation enhanced by thread-level memory protection across x86, ARC, and ARM architectures, as well as userspace and memory domains. For systems lacking MMU/MPU and those limited by memory capacity, it enables the integration of application-specific code with a tailored kernel to form a monolithic image that can be loaded and run on the hardware of the system. In this setup, both the application and kernel code operate within a unified address space, facilitating efficient resource utilization and performance optimization. This design ensures that even resource-constrained environments can effectively leverage complex applications and functionalities.

Azure RTOS is a comprehensive embedded development suite that features a compact yet robust operating system, delivering dependable and ultra-fast performance tailored for devices with limited resources. Its user-friendly design and proven market success have led to its implementation in over 10 billion devices globally. Additionally, Azure RTOS is compatible with a wide array of popular 32-bit microcontrollers and embedded development tools, enabling teams to leverage their existing expertise effectively. The suite facilitates seamless connections to both cloud and local networks, aids in the creation of resilient flash file systems, and supports the development of sophisticated user interfaces. The code provided has been validated to adhere to rigorous industry safety and security regulations. Moreover, well-structured and comprehensible code enhances usability and maintenance, potentially reducing overall ownership costs. It is important to note that many safety-related certifications mandate the submission of the entire source code for your software, which includes the RTOS component, ensuring transparency and compliance with safety standards. In this way, Azure RTOS not only streamlines the development process but also aligns with industry requirements for safety and reliability.