If you like the idea of tracking your blood work but not of keeping it on someone else's servers, here is what to compare and how an on-device app like Delta differs.
Services like Function Health made regular, broad blood testing popular. As we understand it at the time of writing (September 2026), it is a US membership: it orders a large panel of lab tests at partner labs and shows your results in an account on its platform. For many people that is a good fit.
Some people want something different. They already get blood work through their doctor or a lab of their choice, and they would rather their results did not live in another company's database. This post is for them.
Who draws your blood? Membership services bundle the test with the platform. Other routes include your own doctor, your insurer, or a direct-to-consumer lab. The markers that matter for a blood-based biological age are routine and widely available.
Where do your results live? This is the privacy question. With an account-based platform, your full history sits on its servers. With an on-device app, it sits on your phone.
You can pick your answer to each question separately. You do not need a membership to track your results over time.
Delta is a free app for iPhone and Android. It has no accounts: no email, no password, no sign-in. Your blood panels, scores, and history are stored on your phone. Delete the app and they are gone.
When you add a report, it is read by our analyzer and then discarded. No report, photo, or marker value is kept on our servers. We hold two things, both keyed to a random device identifier: the persona you choose or describe, and the daily read the app writes for you. Daily reads are deleted automatically after 30 days, and you can erase both any time from inside the app. Our privacy policy lists all of it.
Your Adaptive Age is computed on your device from nine routine markers, using the published PhenoAge formula. The same panel always gives the same number.
Delta does not order lab tests or draw blood. You bring a report from any lab. It also does not give medical advice: it is a wellness app that shows your numbers and how they change over time.
If you have a recent panel, you can see your Adaptive Age in a few minutes, without creating an account. Get Delta.
