Why a private period tracker actually matters in 2026.

The thing most people don't know

When you open a typical period tracking app and log "Day 1," that piece of information usually doesn't stay in the app. It travels.

It gets bundled into a data point. The data point gets sent to an analytics provider so the company can chart user behaviour. It gets sent to an ad network so the app can show you better-targeted ads. It gets shared with "wellness partners" who might want to advertise prenatal vitamins, fertility products, or birth control to you based on where you are in your cycle. Sometimes it gets sold to data brokers who package and resell it.

None of this is hypothetical. Investigations by the Wall Street Journal, the Markup, Mozilla, and the FTC have all documented period apps doing exactly this — including with companies the user has never heard of.

"But the app said it was private"

Most app privacy policies say roughly: "we may share your data with trusted third parties to provide and improve our services." That single sentence is doing an extraordinary amount of work. It covers everything from a legitimate cloud database to ad targeting based on whether you're trying to conceive.

The thing is — once your data is on a server somewhere, you can't take it back. You can't un-share it. You can delete your account, and the company might honour that, but you'll never know whether the data also lived in a partner's warehouse, an ad broker's catalogue, or a backup snapshot taken last week.

Why this isn't only a privacy issue

Period data is unusually sensitive because it implies things about your life that you probably haven't told anyone — pregnancy, miscarriage, hormonal conditions, sexual activity, whether you're trying to conceive. In some jurisdictions in 2026, this data has been subpoenaed by law enforcement. Anywhere, it's exactly the kind of data that insurance companies, employers, and advertisers would pay a lot to access.

The safest data is data that does not exist outside your own device.

What "on-device only" actually means

Dew was built so that this entire chain is structurally impossible.

There is no Dew server holding your cycle history. We don't run analytics on your entries. We don't have an account system, so there is no profile to share. There are no third-party SDKs in the app collecting events. We use Apple's on-device language model for any AI features, so even those reflections never leave your phone.

We can't sell your data to data brokers because we don't have it. We can't hand it to law enforcement because we don't have it. We can't accidentally leak it in a breach because there's no Dew database that could be breached.

This isn't a privacy promise we hope to keep. It's a property of how the app is built.

How to tell whether any period app is actually private

Before you trust any period tracking app — including ours — check these things:

• Does it require an account or email? If yes, the company holds your identity. Avoid.
• Does the privacy policy mention "partners," "third parties," "ad networks," or "analytics providers"? Read carefully. Anything beyond Apple-platform services (App Store crash reports) is a yes-it-leaves-your-phone signal.
• Can it work offline? If not, that's a strong hint your data is syncing somewhere.
• Is it free with no clear business model? Free + no ads + no paid tier usually means you're the product.
• Where is the company based? Different jurisdictions have very different rules about handing health data to authorities.

Where Dew lands on each of those

• No account required. Ever.
• No third parties in the privacy policy. Read it here — there's nothing to share with, because we don't share with anyone.
• Works fully offline. The app doesn't need a network connection.
• Pricing is honest. Free during v1, then a small one-time price plus optional monthly Pro for advanced features. We make money from people, not from advertisers.
• Architecture is the protection. Even if subpoenaed, we have nothing to hand over.

If you only remember one thing

Your cycle is a private thing. The app you track it in should also be a private thing.

Dew is one of those — and we hope, when it ships, you find it small enough to trust.