Where does my period data live?

On your iPhone. Only on your iPhone. Nowhere else. If your phone is lost, your data is lost — we can't recover it, because we never had a copy.

Is Dew a private period tracker?

Yes. Dew has no account, no email collection, no ads, no third-party trackers, and no data sold to anyone. Your cycle logs stay on your iPhone — we have no way of knowing who you are.

Does Dew use iCloud sync?

Optional. If you turn iCloud sync on, your data lives in your own private iCloud, encrypted so only your Apple devices can open it. We don't see it. Apple can't read it.

Where are insights generated — on my phone, or somewhere else?

Insights are written entirely on your iPhone by Apple's on-device language model. No prompts, no data, no outputs ever leave the device — no one but you can see them.

How much does Dew cost?

Dew is free during v1. When pricing arrives in v1.1+, there will be a small one-time price for core tracking and a small monthly Pro tier for advanced features. Both are honest. No surprises, no dark patterns.

Because accounts mean we'd have to keep something about you. We don't want to. The whole app is built so it's impossible for us to know who you are.

Flo, Clue, Stardust, Dew: a privacy comparison

Four trackers, six privacy questions, side by side. Where your data lives, what's encrypted, who can read it, and what survives an uninstall.

"Privacy" in period app marketing has become a word that means everything and therefore nothing. Every app claims it. We wanted to know what it actually meant for the four most-installed cycle trackers in 2026.

Below: the same six questions asked of each app, answered from public privacy policies, FTC filings, and the apps' own technical documentation. Plain facts, no FUD.

The six questions

Where does your data physically live?
Is the data encrypted at rest? With what key?
Does the app share data with third parties, and if so, who?
Is there a way to use it without an account?
How long does account deletion take, and what survives?
What happens to your data if the company is acquired or goes bankrupt?

1. Where does the data live?

Flo: AWS servers, primarily US East.
Clue: AWS servers in Germany (EU jurisdiction).
Stardust: AWS servers, US.
Dew: Your iPhone, locally. Optional sync to your own iCloud Private Database. Dew has no servers of its own.

2. Encryption at rest?

Flo: At rest on Flo's servers, encrypted with Flo's keys. They can decrypt it; you can't.
Clue: Same — encrypted at rest on Clue's servers with Clue's keys.
Stardust: Same.
Dew: Local SQLite database, OS-level encryption when the phone is locked. iCloud sync uses Apple's CloudKit Private Database, which is end-to-end encrypted with your iCloud keys — Apple cannot read it, Dew cannot read it.

What this means: Server-side encryption protects against a stolen hard drive at AWS. It does NOT protect against a subpoena to the company — they have the keys to decrypt, so they can be compelled to. End-to-end encryption with your own keys does protect against subpoena because nobody else can decrypt.

3. Third-party sharing?

Flo: Pre-2021: shared with Facebook, Google, AppsFlyer (per FTC settlement). Post-2021: privacy policy lists "service providers" without naming ad partners. Anonymous Mode is opt-in and lets you skip the account tie. Still uses analytics SDKs by default.
Clue: Shares aggregated, anonymized data with research partners (Stanford, Oxford, named in their transparency report). Does not share with ad networks.
Stardust: Has shared data with third parties in the past (per The Markup, 2022). Practices have updated; the policy doesn't fully exclude future sharing.
Dew: No third-party SDKs at all. Anonymous, opt-out usage analytics through TelemetryDeck — only feature taps, never cycle data. Crash reports through Apple's own MetricKit. Privacy policy.

4. Usable without an account?

Flo: No. Account creation is required at install.
Clue: No. Account required.
Stardust: No. Account required.
Dew: Yes. There is no account system. Install, open, log.

5. Account deletion time / what survives

Flo: Within 30 days. Anonymized aggregate already shared with third parties is not pulled back. The FTC consent decree from 2021 means any older data shared with Facebook/Google/AppsFlyer is also outside their control.
Clue: Within 30 days. Aggregated anonymized data used in published research isn't pulled back (research-ethics norm).
Stardust: Within 30 days per policy. Anything previously shared with third parties not under their control.
Dew: Immediate. "Delete All" in Settings wipes the local database and force-pushes the truncate through your iCloud sync so other devices converge before sign-out. Nothing on Dew's servers because Dew has no servers.

6. What happens if the company is acquired or goes bankrupt?

Flo: Data is an asset on Flo's balance sheet. In an acquisition, it transfers. In a bankruptcy, it could be sold (this is what happened to Vine, MoviePass, and several health apps).
Clue: Same risk in principle, mitigated by GDPR (the data can't be transferred to a buyer who can't honor GDPR commitments).
Stardust: Same risk as Flo.
Dew: Even if Dew shuts down tomorrow, your data is in your own iCloud Private Database — Dew cannot transfer it, sell it, or look at it. Your data outlives the company.

The summary table

Same answers, easier to scan:

	Flo	Clue	Stardust	Dew
Data on company servers?	Yes	Yes	Yes	No
End-to-end encrypted?	No	No	No	Yes
Third-party SDKs?	Yes	Limited	Yes	No
No-account option?	No	No	No	Yes
Subpoena-reachable?	Yes	Yes	Yes	No
Survives company shutdown?	No	Partial	No	Yes

The honest take

Clue is the best of the cloud-stored options — German jurisdiction, no ad networks, transparent about research sharing. If you want a cloud-tied tracker, that's the one.

Dew is the only one in the four where the privacy properties are structural rather than contractual. The others are trusting their company to follow its own policy. Dew can't break the policy because the architecture doesn't allow it.

Flo and Stardust are not bad apps. They have features (large communities, broader symptom libraries, partner sharing) the more-private options don't yet. If those features matter more to you than privacy, install those — just go in with eyes open about what you're trading.

For more, see the best private period tracker apps in 2026 and are period tracker apps safe?