µC/OS Licensing

The µC/OS components are offered under a permissive, open-source Apache 2.0 license model. Under this model, developers seeking to use the components may download and use the software at no cost.

This change is a substantial one and was made after careful consideration of the current environment for software development.  By adopting permissive license terms for the µC/OS components, this now brings the software’s rich set of features and benefits within reach of the widest user base possible and affords the embedded community a role in its future evolution.

A key objective of migrating to the Apache 2.0 License was to minimize the implications for developers who had previously purchased a license to use the µC/OS software. For most licensees, there shouldn’t be any immediate action required. Technical support services  for the µC/OS software is readily available to all customers currently using or interested in the µC/OS family of RTOS components. Additionally Cesium RTOS, the commercial version of the µC/OS software, is also available.

If you have questions about how the change to open-source licensing may affect you, please feel free to contact us.



I previously purchased a µC/OS commercial license from Micrium or Silicon Labs. Is it still valid?

Licenses sold prior to the open-source transition are valid only for the development scenarios that they covered. You will no longer be able to receive technical support or software maintenance directly from Micrium or Silicon Labs. Technical support services are available from Weston Embedded Solutions.

Can I use my previously purchased µC/OS commercial license to develop new products?

You may not develop new products with your previously purchased commercial license unless indicated in the license type you purchased. Prior commercial licenses remain valid only for the development scenarios that they covered when purchased.

What's the difference between µC/OS and Cesium RTOS?

Cesium RTOS is the commercial version of µC/OS and represents the next generation of the software's improvements. Cesium RTOS retains the same set of API's found in µC/OS. This allows for a seamless replacement with no learning curve required by your team.  A comparison and more information can be found here.

What are my options if I wish to develop new products with Micrium's µC/OS software?

If you want to use the µC/OS software for new product development you have two choices:

  • Obtain a license for the commercial version of the µC/OS software, Cesium RTOS, which is actively maintained and supported by Weston Embedded Solutions.
  • Use the µC/OS open source release from the Github repository.


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