List of the Top 9 Real-Time Operating Systems (RTOS) for Windows in 2025

Created through a partnership with leading chip manufacturers over a period of 15 years, FreeRTOS is currently downloaded roughly every 170 seconds and is recognized as a premier real-time operating system (RTOS) designed specifically for microcontrollers and small microprocessors. It is freely accessible under the MIT open source license and features a core kernel along with a growing suite of IoT libraries that serve various sectors. Emphasizing reliability and ease of use, FreeRTOS has garnered a reputation for its robust performance, lightweight design, and broad compatibility with numerous devices, making it the preferred choice for microcontroller and small microprocessor solutions among major global companies. Users benefit from a variety of pre-configured demos and IoT reference integrations, which facilitate straightforward project setups, thus allowing for rapid downloading, compiling, and quicker market entry. This efficient approach not only streamlines development but also supports faster innovation cycles. Additionally, the ecosystem of partners provides a wide array of options, bridging community-driven initiatives with professional support, ensuring users have the vital resources necessary for their success. As the landscape of technology evolves, FreeRTOS is dedicated to continually adapting and enhancing its features to address the shifting needs of the industry, proving its resilience and relevance in a dynamic environment. Moreover, its ongoing commitment to innovation positions it as a key player in the future of real-time operating systems.

Arm Mbed OS is a freely available operating system specifically designed for Internet of Things (IoT) applications, equipping developers with the essential resources to create advanced IoT devices. This powerful operating system is optimized for smart and connected products that utilize Arm Cortex-M architecture, providing features like machine learning capabilities, secure connectivity options, an RTOS kernel, and drivers for a range of sensors and I/O devices. Tailored for the needs of the Internet of Things, Arm Mbed OS encompasses functionalities in connectivity, machine learning, networking, and security, along with an extensive library of software, development boards, tutorials, and real-world examples. It encourages collaboration within a broad ecosystem, supporting over 70 partners across various sectors, including silicon manufacturers, module developers, cloud service providers, and OEMs, thus broadening the options available for developers. By utilizing the Mbed OS API, developers can produce clean, portable, and easy-to-manage application code while also taking advantage of enhanced security, communication, and machine learning features. This integrated solution not only simplifies the development process but also significantly reduces costs, shortens development time, and mitigates risks. Moreover, Mbed OS facilitates innovation by allowing developers to quickly prototype and confidently deploy IoT solutions, ultimately driving technological advancement in the field. The comprehensive support provided by the Mbed community further enriches the development experience, making it an ideal choice for both novice and experienced developers alike.

RT-Thread, which stands for Real Time-Thread, is a multi-threaded operating system specifically built for embedded real-time applications. This operating system is designed to facilitate multi-tasking, enabling various tasks to operate concurrently. While a single processor core can only handle one task at a time, RT-Thread manages to execute all tasks swiftly and alternates between them based on their priority, which gives users the perception that tasks are running simultaneously. Primarily developed in the C programming language, RT-Thread is straightforward to comprehend and transfer to different environments. It employs object-oriented programming techniques in the design of real-time systems, leading to code that is not only elegant and structured but also modular and highly customizable. RT-Thread is available in various editions. The NANO version features a compact kernel that requires merely 3KB of flash memory and 1.2KB of RAM, making it suitable for devices with limited resources. Additionally, for more capable IoT devices, RT-Thread supports an online software package management tool in conjunction with system configuration utilities, facilitating a user-friendly and rapid modular design process. This versatility allows developers to easily adapt the system to meet their specific project needs.

The SCIOPTA architecture is expertly designed to deliver exceptional real-time performance while keeping its dimensions compact. Its internal data structures, memory management strategies, interprocess communication mechanisms, and time management features are all optimized for peak efficiency. Operating as a pre-emptive real-time kernel, SCIOPTA is capable of handling interrupts at any time, even while the kernel is actively executing tasks. This operating system employs a message-based framework, offering a comprehensive set of system calls that enhance effective resource allocation and management. By utilizing standardized processes and interprocess communication protocols, SCIOPTA fosters system designs that are not only straightforward to implement but also easy to maintain over time. The robust messaging system facilitates seamless communication between processes and allows for the organization of processes into coherent modules, making SCIOPTA particularly beneficial for collaborative projects of considerable scale. Additionally, the streamlined architecture significantly shortens time-to-market, thereby improving overall project efficiency. Furthermore, the direct message passing feature not only supports interprocess communication but also aids in synchronization, which further refines system performance, making SCIOPTA a valuable asset in any development environment. Its ability to handle complex project needs with ease underscores its versatility and effectiveness.

Deos™, created by DDC-I, is a real-time operating system (RTOS) focused on safety and rigorously verified in alignment with DO-178C/ED-12C Design Assurance Level A (DAL A) standards for avionics use. This RTOS is compatible with ARINC 653 APEX and employs rate monotonic scheduling (RMS), specifically engineered to fulfill the FACE Safety Base Profile requirements. Since receiving its initial verification from Transport Canada in 1998, Deos has established itself as a reliable solution within the aviation sector, earning certification that permits its operation in countless aircraft. Over the last twenty years, it has continually adapted, integrating new processors and features to showcase its versatility and robustness. Additionally, Deos has successfully passed audits from numerous global certification bodies such as the FAA, ENAC, JAA, EASA, and CAAC, along with assessments by designated engineering representatives from various avionics and airframe manufacturers, guaranteeing that it remains in compliance with the highest industry standards. This ongoing commitment to development and verification not only reinforces its reliability but also positions Deos as an essential element in the landscape of modern aviation safety systems. Furthermore, its ability to evolve alongside technological advancements ensures that it remains at the forefront of safety-critical software solutions.

INTEGRITY utilizes robust hardware memory protection to effectively separate and protect embedded applications. By employing secure partitions, it guarantees that each task can access the necessary resources for optimal performance while concurrently safeguarding both the operating system and user tasks against malicious and erroneous code, including threats such as denial-of-service attacks, worms, and Trojan horses. To assist developers in accelerating their product development, Green Hills Software offers an extensive suite of middleware that has been thoroughly integrated and validated for compatibility with INTEGRITY, which features file systems like FFS, FAT, NFS, and journaling, alongside IPv4 and IPv6 networking stacks and a FIPS 140-2 certified Suite B embedded encryption library, among many other essential tools. Each middleware package has successfully passed rigorous pre-integration testing to ensure seamless functionality with the advanced features of INTEGRITY's real-time operating system. Additionally, Green Hills Software provides specialized platforms tailored for different industries, creating a fully integrated ecosystem that includes the INTEGRITY RTOS along with critical development tools, all aimed at further simplifying the development process. This comprehensive strategy not only enhances operational efficiency but also significantly fortifies the security of embedded applications, ensuring they can withstand various cybersecurity threats effectively.

PikeOS is an advanced hypervisor built on a separation kernel, designed to enable numerous partitions for various operating systems and applications. This platform facilitates the development of intelligent devices tailored for the Internet of Things. Renowned for its robust protection against cyber-security threats, PikeOS is an ideal solution for systems needing stringent security measures, thanks to its innovative separation kernel design. It enjoys widespread adoption, being utilized in millions of edge and IoT devices, and has also found applications in essential communications infrastructure. PikeOS merges virtualization and real-time capabilities through pioneering technologies that are unparalleled in the industry. Additionally, it allows for the integration of multiple intricate embedded circuit boards onto a single hardware platform. Furthermore, PikeOS demonstrates versatility by accommodating new hardware architectures, such as Big-SoCs, which incorporate various heterogeneous cores. This hypervisor is compatible with multiple architectures and can support processors equipped with a memory management unit (MMU). With its unique capabilities, PikeOS stands out as a leading solution in the realm of secure and efficient computing.

This system encompasses a wide array of devices, from fundamental embedded environmental sensors and LED wearables to sophisticated embedded controllers, smartwatches, and IoT wireless applications, featuring a configurable architecture that includes stack-overflow protection, permission tracking for kernel objects and device drivers, and enhanced thread isolation through thread-level memory protection across various architectures such as x86, ARC, and ARM, along with distinct userspace and memory domains. Additionally, for systems that do not have a Memory Management Unit (MMU) or Memory Protection Unit (MPU) and those constrained by limited memory, it facilitates the combination of application-specific code with a customized kernel to create a monolithic image that can be seamlessly loaded and executed on the hardware. Within this framework, both the application and kernel code function within a single address space, promoting efficient resource management and performance enhancements. Consequently, this architecture is adept at enabling even the most resource-limited environments to effectively utilize advanced applications and sophisticated functionalities, thereby broadening the scope of what can be achieved in embedded systems.

Azure RTOS stands out as a versatile embedded development framework, featuring a lightweight yet powerful operating system that ensures reliable and swift performance for resource-constrained devices. Its easy-to-navigate interface, paired with proven success in the marketplace, has resulted in its adoption by over 10 billion devices worldwide. Furthermore, Azure RTOS is designed to work seamlessly with a broad spectrum of popular 32-bit microcontrollers and embedded development environments, allowing development teams to utilize their existing skills efficiently. The suite supports effortless connectivity to both cloud and local networks, assists in crafting durable flash file systems, and enables the creation of advanced user interfaces. The code produced is rigorously tested to meet stringent industry safety and security standards. In addition, well-organized and easily understandable code not only improves usability and maintenance but also helps lower overall ownership costs. It is critical to recognize that numerous safety certifications require the full disclosure of the entire source code, including the RTOS component, to ensure compliance and transparency with safety regulations. Thus, Azure RTOS not only simplifies the development workflow but also meets industry standards for both safety and reliability, making it a preferred choice for developers in the embedded systems domain. This comprehensive approach positions Azure RTOS as an essential tool for modern embedded applications.