Health Tracking Apps That Don't Sell Your Data (And How to Check)
Most health apps make money twice: once from you, once from your data. Here's how to actually check what an app does with your health information.
Most health and fitness apps have two revenue streams: what you pay them, and what they sell about you. The second one is rarely mentioned in the App Store description, and it's usually the more valuable one.
What "selling your data" actually looks like
It's rarely a direct sale of your name and sleep schedule to a stranger. It's aggregated behavioral data going to advertising networks, "anonymized" datasets sold to data brokers, or health metrics feeding a recommendation engine that shares insights with third-party partners. Read the privacy policy of any major free tracking app and look for the words "third parties," "advertising partners," or "aggregated data" - it's almost always there.
How to actually check, not just trust the marketing
- Read the data-sharing section of the privacy policy, not the marketing page. The privacy policy is the legal commitment; the marketing page is the pitch.
- Check what happens if you delete your account. If the answer isn't a full, immediate deletion, your data likely lives on somewhere.
- Look at where the analysis runs. If a claim like "AI-powered insights" requires uploading raw health data to a server to work, that data now exists outside your device, permanently.
Where Evident draws the line
Evident's correlation analysis, the actual statistics behind every insight, runs on-device. Your health data doesn't need to leave your phone to compute a Pearson correlation between your sleep and your mood. Evident doesn't sell data to third parties, doesn't run ads, and doesn't have a revenue model that depends on your data being valuable to someone else, because there isn't one: Evident is free.
Why this matters more for health data specifically
Financial data gets stolen and you can freeze a card. Health data is different: it doesn't expire, it can't be reissued, and it reveals more about you than almost any other category of information, sleep patterns, mood, activity, sometimes fertility or medication tracking. Once it's shared, there's no undo.
The trade-off that isn't real
Free tracking apps often imply you're trading privacy for a free product. That trade only exists because most free apps need a second revenue stream to survive. Evident's free tier isn't the ad-supported kind of free, there's no second stream, no data-for-features exchange. Free and private aren't in tension here, they were never supposed to be.
Download Evident, completely free, and check its privacy policy yourself before you trust ours or anyone else's blindly.