A period tracker with no account: why the sign-up screen is the weakest link
You download a period app. Before you can log a single day, it wants an email address and a password. Maybe a phone number. Maybe it offers to let you sign in with Google, which is faster and also worse.
It’s such a standard piece of app furniture that most people tap through without thinking about it. But it’s worth asking what that screen is actually for, because in a cycle tracking app, it’s rarely for you.
What an account is really doing
An account exists so that a server can recognise you across sessions. That’s its entire function. Everything else follows from it.
Which means that if an app requires an account, you can infer how it’s built without reading a word of the privacy policy: your data is on a server, associated with an identifier that points back to you. Not on your phone. On a machine owned by a company, sitting in a database, alongside everyone else’s.
That database is what gets breached. It’s what gets subpoenaed. It’s what shows up on the balance sheet when the company is acquired and the new owner rewrites the privacy policy. It’s what an advertising tool has access to when it’s bundled into the app to help the business monetise.
None of this requires anyone at the company to be acting in bad faith. In the Flo case, court filings described reproductive health data reaching Meta and Google through standard advertising and analytics tools (the ordinary plumbing of a modern app, doing what that plumbing does). The data was reachable, so it was reached.
An app with no account has no such database. Not a well-secured one. Not one.
But don’t I need it to keep my data safe?
This is the reflex, and it’s backwards for this particular kind of app.
The intuition comes from things like email and banking, where the whole point is access from anywhere, and where a cloud copy is genuinely protective. Cycle tracking isn’t that. You log from one device: your phone, the one in your hand. You almost never need to check your period history from a laptop in a different city.
The thing an account buys you is cross-device sync. Which is real, but it’s a convenience feature, and it’s worth being clear-eyed that you’re paying for it with a server-side copy of the most sensitive data you generate.
What actually protects local data:
- Your phone’s device encryption, which is on by default on any modern iPhone
- Your passcode or Face ID
- An app-level lock, so someone who’s already past your lock screen still can’t open it
- Your regular device backup, which is what carries your history to a new phone
That last one matters. Local-only doesn’t mean “one drop and it’s gone.” It means your history rides along with your normal iPhone or Android backup, the same way your photos and messages do. It’s the same recovery path you already rely on for everything else on your phone.
The honest trade-offs
An app with no account gives up some real things, and you should know what they are before you switch:
No recovery from the company. If you lose your phone and don’t have a device backup, nobody can restore your history, because nobody else ever had it. This is the direct consequence of the thing that makes it private.
No effortless cross-device use. You can’t log on your phone and review on a tablet without going through your device backup.
No “log in on your new phone and everything’s there.” You restore from backup instead.
Less personalisation from aggregate data. Apps with large server-side datasets can compare your patterns against millions of others. A local-only app works from your data alone. In practice this matters less than it sounds (the statistics that drive cycle prediction work fine on your own history), but it’s a real difference.
What you get in exchange is that there is no copy of your reproductive health record anywhere except your own device. No breach can expose it, no policy change can reinterpret it, no acquisition can transfer it, and no ad network can reach it.
For a lot of people that’s an easy trade. For some it isn’t. Both are reasonable.
How to tell if an app is genuinely local
Two tests, both quick:
The sign-up test. If it asks for an email, phone number, or social login before you can use it, there’s a server.
The airplane mode test. Turn off wifi and cellular, open the app, log something, scroll your history. If it all works normally, nothing is round-tripping to a server. If it hangs or errors, your data is going somewhere.
Worth doing on any health app you already use. The results are sometimes surprising.
How Lua works
There’s no sign-up in Lua. No email, no password, nothing to verify, nothing to remember. You open it and start using it.
That’s possible because there’s no Lua account to sign into, and no Lua server holding your logs. Everything you log (periods, symptoms, contraception, sex, pregnancy) is written to private storage on your own phone and stays there. We can’t read it, because it never reaches us. No advertising, and no analytics of what you track. You can turn on a Face ID lock so nobody else can open it either. If you buy Lua+, Apple processes the payment; that receipt is not your cycle history.
If you want to bring your history with you, Lua can import up to the last 12 months of period entries from Apple Health on first launch, so you’re not starting from zero. That stays off until you turn it on, and it only ever exchanges menstrual flow. Your symptoms, notes and sex logs are never written to Health. More on how that works on our period tracker page, and the full detail is in our privacy policy.
And the trade-off, stated plainly: because your data lives only on your device, we have no copy to restore it from. Your phone’s backup through Apple is what carries your history to a new device. No cloud copy means nothing to leak, but also nothing for us to recover.
Lua is on the App Store for iOS. Tracking is free, with no ads. Lua+ is optional and billed by Apple: it unlocks reminders for every method and full cycle stats.
Lua is not a contraceptive and has no contraceptive effect. Always follow your prescriber’s instructions.
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