Can I Build a Privacy-Focused Oura-Like Ring Without a Subscription?

The hardware is the difficult part. Fitting a battery, Bluetooth connection, heart-rate sensor, and possibly temperature sensing into a reliable ring is much harder than writing the software. For a DIY project, it would make more sense to buy an inexpensive ring and work on local data collection rather than manufacture the device itself. A used wearable that doesn’t require a subscription could also be worth considering.

The COLMI R02 is one possible starting point. People have experimented with connecting to it over Bluetooth and reading sensor data locally, although it doesn’t include temperature sensing. The R09 is a slightly more expensive alternative that does include a temperature sensor.

Rather than trying to jailbreak or reverse-engineer a premium ring, look into existing Bluetooth projects for the COLMI R02 or R09. There are Python scripts that can connect to these devices and retrieve readings such as heart rate, allowing you to store the data on your own computer or phone. Your friends could adapt that code into a local database or app. It still may require reverse engineering and the measurements may not be as polished or complete as those from a commercial device, but it’s a much more realistic project than building the ring hardware from scratch.

You may have better luck starting with a smartwatch instead of a ring. Devices such as the PineTime and other developer-friendly watches have more space for sensors and batteries, plus they’re easier to program, open, and troubleshoot. The tradeoff is that they’re obviously larger than a ring.