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The Zephyr Project is a Linux Foundation hosted Collaboration Project. It’s an open source collaborative effort uniting developers and users in building a best-in-class small, scalable, real-time operating system (RTOS) optimized for resource-constrained devices, across multiple architectures.

The Zephyr Project is a neutral project where silicon vendors, OEMs, ODMs, ISVs, and OSVs can contribute technology to reduce costs and accelerate time to market for billions of connected embedded devices. The software is a perfect choice for simple connected sensors, LED wearables, modems, and small wireless gateways. Because Zephyr is modular and supports multiple architectures, developers can create a solution that meets their needs.

As an open source project, the community evolves the project to support new hardware, developer tools, sensors, and device drivers. Improvements are frequently delivered to incorporate enhancements in security, device management capabilities, connectivity stacks, and file systems.

Why create another RTOS?

Change is happening fast in the connected devices space, and the technical requirements are vast. No one person or company has all the answers. Collaboration is key to driving down costs and accelerating time to market. A platform to facilitate collaboration must be commercially neutral, inclusive of all contributors, and governed such that all interests are fairly represented.

That’s why the Zephyr Project was created. We’re using an open, collaborative environment to deliver an RTOS that’s open source, applicable in a wide diversity of use cases, and currently supports more than 170 hardware devices, more than any other RTOS, while giving members a clear path for upstreaming code and participating in the future roadmap.

Engage with our community. We’re happy to answer your questions and share how becoming a member of the Zephyr Project was the right choice.

Learn more about the benefits of using Zephyr in your application.


Zephyr is a full-featured OS with an architecture that allows developers to focus on the application.

  • Highly configurable and modular
  • Supports cooperative and preemptive threading
  • Memory and resources are typically statically allocated, benefitting long-running systems
  • An integrated device driver interface
  • Offers memory protection via stack overflow protection, kernel object and device driver permission tracking, and thread isolation
  • Bluetooth® Low Energy (BLE 4.2, 5.0) support, with both controller and host, BLE Mesh
  • 802.15.4 OpenThread compliant
  • A native, fully featured and optimized networking stack
  • Supports a range of subsystems, including USB, filesystem, logging, DFU



  • Developed with security in mind
  • Employs an in-depth security development lifecycle: security validation, fuzz and penetration testing, frequent code reviews, static code analysis, threat modeling and reviews to prevent backdoors in the code
  • Includes CNA with Product Security Incident Response Team (PSIRT) response team
  • The project’s governance includes the formation of a security working group and a delegated security maintainer
  • The governance and its members have a responsibility to ensure that all aspects of the code are developed securely
  • Level 1 certification in the Platform Security Architecture (PSA) certification scheme
  • Functional safety coming soon

Open Source

  • Available through the Apache 2.0 open source license
  • Free to use in commercial and non-commercial solutions
  • Hosted as a collaborative project with the Linux Foundation, the project is neutrally governed and employs a lightweight governance and development model
  • From professional makers to large industrial and commercial vendors, the Zephyr Project strives to deliver a universally adoptable solution for the Internet of Things

Product Ready

  • Long term support (LTS) with security updates
  • Certification-ready with Auditable


  • Full-featured and power optimal: fully preemptible tickless kernel
  • Advanced memory management: Userspace support
  • Multi-processor support: SMP and AMP 
  • Build for your architecture: Both 32 and 64-bit supported

Modular and Scalable

  • the Zephyr Project provides developers with feature-rich software optimized for memory constrained devices
  • Runs on systems as small as 8 kB of memory but scales up to systems with megabytes or even gigabytes of memory” (we now have 64-bit support)
  • Developers can use their tool suite of choice by supporting custom toolchains and compiler optimizations
  • Manage multi-repo configurations with West where it is possible to have cross-repo version control and build inclusion of entire independent project repos, including your own

Powerful Configuration Tools

  • Kconfig and Device Tree are part of the Zephyr platform
  • RTOS can be built as-is, with default configuration, or as a tailored solution by enabling/disabling features using Kconfig
  • Build applications to target different boards, and even architectures via Device Tree


  • Optimized for low-powered, small memory footprint devices
  • Supports Bluetooth®, Bluetooth® Low Energy, Wi-Fi, 802.15.4
  • Supports standards like 6LoWPAN, CoAP, IPv4, IPv6, Ethernet, USB, CAN and Thread