I think Ultrahuman ring is not opensource, however, the company maintains an "open-ecosystem" approach in several ways.

• Proprietary Core: The main mobile applications (iOS/Android) and the device firmware are closed source to protect their intellectual property and medical algorithms.

• Open API: Unlike many competitors, Ultrahuman provides an Open API. This allows users and developers to access their own health data to build custom dashboards or integrations.

• Developer Community: They host several public repositories on GitHub, sharing specific libraries, UI components, and SDKs to help developers build for their platform.

• PowerPlugs: This is their "app store" for health features, which encourages third-party developers to create plugins that extend the functionality of the ring.