Trace Id is missing
Skip to main content

Azure RTOS

Making embedded IoT development and connectivity easy.

Embedded IoT device development made easy

Azure RTOS is an embedded development suite including a small but powerful operating system that provides reliable, ultra-fast performance for resource-constrained devices. It’s easy-to-use and market-proven, having been deployed on more than 10 billion devices worldwide. Azure RTOS supports the most popular 32-bit microcontrollers and embedded development tools, so you can make the most of your team’s existing skills.

Predictably fast performance and a remarkably small footprint

Easily connect to cloud and local networks, develop durable flash file systems, and design elegant user interfaces

Seamlessly connect the most popular MCUs and MPUs to the power of Azure IoT

Code that has been certified to meet stringent industry safety and security standards

Azure RTOS components

Azure RTOS ThreadX

This advanced real-time operating system (RTOS) is designed specifically for deeply embedded applications. Among the multiple benefits it provides are real-time multithreading, inter-thread communication and synchronization, and memory management. Azure RTOS ThreadX has many advanced features, including picokernel architecture, preemption threshold, event chaining, and a rich set of system services.

A hand placing a chip inside a machine

Azure RTOS FileX

This is a high-performance, file allocation table (FAT)-compatible file system that’s fully integrated with Azure RTOS ThreadX and available for all supported processors. Like Azure RTOS ThreadX, Azure RTOS FileX is designed to have a small footprint and high performance, making it ideal for today’s deeply embedded applications that require file management operations.

Azure RTOS GUIX Studio and GUIX

Azure RTOS GUIX Studio provides a complete, embedded graphical user interface (GUI) application design environment, facilitating the creation and maintenance of all graphical elements in the application’s GUI. Azure RTOS GUIX Studio automatically generates C code that’s compatible with the Azure RTOS GUIX library, ready to be compiled and run on the target.

Azure RTOS TraceX

Azure TraceX is a Windows-based analysis tool. It provides embedded developers with a graphical view of real-time system events and enables them to visualize and better understand the behavior of their real-time systems. With TraceX, embedded developers can clearly see the occurrence of system events like interrupts and context switches that occur out of view of standard debugging tools.

Azure RTOS NetX

A high-performance implementation of TCP/IP protocol standards (IPv4 only), Azure RTOS NetX is fully integrated with Azure RTOS ThreadX and available for all supported processors. It has a unique piconet architecture. Combined with a zero-copy API, it makes it a perfect fit for today’s deeply embedded applications that require network connectivity.

Azure RTOS NetX Duo

This advanced, industrial-grade TCP/IP network stack is designed specifically for deeply embedded real-time and IoT applications. Azure RTOS NetX Duo is a dual IPv4 and IPv6 network stack that provides a rich set of protocols, including security and cloud protocols.


A high-performance USB host and device embedded stack, Azure RTOS USBX is fully integrated with Azure RTOS ThreadX and available for all Azure RTOS ThreadX–supported processors. Like Azure RTOS ThreadX, Azure RTOS USBX is designed to have a small footprint and high performance, making it ideal for deeply embedded applications that require an interface with USB devices.

Back to tabs

Reliable, real-time performance for resource-constrained devices

Achieve ultra-fast, predictable run-time performance with minimum resource consumption. Azure RTOS ThreadX offers sub-microsecond context switching, while Azure RTOS NetX Duo offers near-wire-speed network performance. All components are designed to be deterministic and perform in a fast, predictable manner, regardless of system load.

Preemption-threshold scheduling

Event chaining

Access to source code with simple licensing options

The full source code for all Azure RTOS components is available on GitHub to test and explore. When you’re ready to take your code into production, there’s no charge for the production license if deploying to pre-licensed devices. Simple licensing options are available for all other devices.

Access Azure RTOS code on GitHub

See a list of pre-licensed devices

High-quality, code, right out of the box

Clean, clear code is easier to use and maintain and can lower total cost of ownership. Most certifications require you to submit the complete source code for your software, including the RTOS. With Azure RTOS, you not only get high-quality code—you can also access full reports that verify the code meets stringent test requirements.

Reduce the complexity of connecting to the cloud

Devices are becoming smarter and more powerful than ever. They can collect data and act on it, learn, and make predictions—but only if they’re connected to a robust cloud service. Transitioning to the Internet of Things can feel overwhelming. We’ve made it easy for you. Azure RTOS is seamlessly integrated with Azure IoT so you can connect, monitor, and control your IoT products. Connect via IoT protocols, reference templates, or IoT Plug and Play with the Azure IoT device SDK.

Security for real-time embedded applications

Azure RTOS provides IP and socket-layer security via industry standard protocols and compliance standards. In addition, Azure RTOS uses hardware cryptographic and memory protection capabilities.

Supports IP layer security (IPsec) and socket layer security (TLS and DTLS) protocols

Methodically tested and certified to meet international security assurance requirements

Integrated with Azure Defender to detect threats and remediate issues before they’re exploited

Azure RTOS hardware partners

These partners will provide integrated solutions to help you quickly start prototyping and developing enterprise-ready solutions.

Microchip Technology

Microchip Technology

NXP Semiconductors

NXP Semiconductors



Renesas Electronics

Renesas Electronics



The report titled IoT Signals Manufacturing Spotlight

Read the latest edition of the IoT Signals report

This paper builds on the success of prior reports, uncovering fresh learnings and insights on the state of IoT.

Comprehensive security and compliance, built in

A security center overview in Azure showing policy and compliance data and resource security hygiene
The security center compute and apps tab in Azure showing a list of recommendations

Get started with an Azure free account


Start free. Get $200 credit to use within 30 days. While you have your credit, get free amounts of many of our most popular services, plus free amounts of 55+ other services that are always free.


After your credit, move to pay as you go to keep building with the same free services. Pay only if you use more than your free monthly amounts.


After 12 months, you'll keep getting 55+ always-free services—and still pay only for what you use beyond your free monthly amounts.

Trusted by companies of all sizes

Consumer: HTC fitness device

"We used ThreadX RTOS in our wearable product. It provided good performance. Having full source code and prompt technical support saved development effort a lot."

Garfield Hsieh, Software Sourcing, Fitness Devices, HTC

Rockefeller Capital Management

Semi-conductor: Broadcom WICEDTM system on chip (SOC)

"Broadcom's WICED line of development platforms are enabling breakthrough innovation in a vast number of end applications throughout the IoT ecosystem. By combining our integrated Wi-Fi and Bluetooth technology with a ThreadX real-time operating system and complete network stack (NetX Duo) in a single, highly integrated platform, developers are armed with all the tools they need to streamline the development process and get to market quickly."

Jeff Baer, Director of Business Development, Broadcom



Networking IoT: Aethra telecommunications

"My experience with ThreadX was very good. In the past, I used other real-time operating systems, but I found ThreadX to be very powerful, robust, and [with] strong real-time—and easy to understand and explain to other team members. We have utilized an object-oriented framework (using C++) around ThreadX to encapsulate it and to add some specific features for multi-applications management."

Bruno Cesanelli, Software Engineer, Aethra

MVP Health Care


Aerospace/defense: NASA Mars Reconnaissance Orbiter

"We found ThreadX to be a proven solution based on its demonstrated success for the Deep Impact mission, so using it for the High-Resolution Imaging Science Experiment (HiRISE) instrument aboard the Mars Reconnaissance Orbiter (MRO) was a logical decision. ThreadX delivered a first-rate performance for us and helped the MRO mission return extraordinary, high-resolution images from Mars."

Steve Tarr, HiRISE Software Lead, Ball Aerospace and Technologies Corp.

Back to tabs

Azure RTOS resources and documentation

Developer resources

How-to guides, tutorials, and API reference documentation

Azure RTOS source code on GitHub

Frequently asked questions about Azure RTOS

  • Microsoft acquired Express Logic, a leading developer of RTOS and middleware products for embedded IoT applications, in April 2019. Read the announcement.

  • The X-WARE IoT Platform was a suite of embedded development products from Express Logic that included ThreadX RTOS. The suite is now Azure RTOS, and ThreadX RTOS is now Azure RTOS ThreadX. The products have improved connectivity to Azure IoT Hub and Azure IoT Central and seamless access to the benefits of Azure IoT. We will continue to enhance the value that Azure RTOS brings to customers and to grow the ecosystem of partners.

  • No, Azure RTOS integrates with other cloud services, but it offers superior integration with Azure IoT.

  • We recommend Azure Sphere for embedded developers who need to build highly secured devices fully prepared for the evolving cybersecurity challenges of the internet for MCU class devices. We recommend Azure RTOS in applications where Azure Sphere isn’t available or a good fit. Azure RTOS provides embedded developers a rich set of real-time multitasking, FAT file system, GUI, USB and networking components to quickly build applications on resource constrained devices – with out-of-the-box connectivity to Azure IoT. Azure RTOS also provides a rich set of pre-certified security components, however, the embedded developer is ultimately responsible for the proper usage of these components and the overall security of the device.

    Azure Sphere and Azure RTOS are ideal together for embedded developers who need a highly secure device with real-time processing capabilities.

  • Azure RTOS support plans are available for purchase. Microsoft ended sales and support of legacy Express Logic products in May 2020, however, support on existing paid contracts will be available through your existing channels ( and

  • Embedded developers typically use a RTOS when they require real-time capability. A RTOS should offer consistently fast response times (in microseconds), a small memory footprint (less than 2 MB), and a level of security that effectively protects users and connected systems.

We’re here to help you get started with Azure

Contact sales for assistance