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Period tracker privacy: EU servers or only on your phone?

Advertising for our own product: this page is published by icoso consulting S.L., the company behind Luna.

Last reviewed: September 24, 2026

Cycle entries can stay on your phone only or sync through servers; both can be privacy-friendly. With apps that use servers in the EU, what matters is which data is encrypted, who holds the keys and which other services receive data. Luna, the app of the publisher of this page, stores synced entries on servers in the EU and encrypts tracking and journal entries on the device first, apart from a few details needed for reminders and syncing. What that means in detail, and where the limits are, we answer below using the same six questions.

Two ways to store cycle data

If an app stores your entries on your phone only, the provider keeps no server copy of them. Account requirements and options for moving your entries to a new phone depend on the app. Also check whether your device backup saves app data to a cloud service.

Apps can use servers to sync and back up your entries across devices; with Luna you need an account for that. Whether this is privacy-friendly depends on more than the server location; the six questions below help you check.

If you want to inspect the code and keep your entries on your phone only, Luna is not the right fit: it is not open source and syncs through servers. Our app comparison shows apps that offer both.

Six questions to check any period tracker

  1. Where are the servers? Does the privacy policy name a location in the EU, and does it cover all data or only part of it?
  2. Which data is encrypted, and who holds the keys? Alongside encryption, check whether the provider can access the key.
  3. Which other services receive data? The list of processors shows which service providers receive data, what for and in which countries they process it.
  4. Is there an independent tracker report? Exodus Privacy checks Android apps for built-in trackers and permissions.
  5. How does the app make money? Subscriptions, advertising or data.
  6. Can you export your data and delete your account from within the app?

These questions apply to Luna too. Here are our answers, each with its source.

Server location

Hetzner Cloud in the EU, run by us. Backups are in the EU as well (Hetzner and Scaleway).

Source: Fact sheet (own statement)

Encryption and keys

Tracking and journal entries (period, symptoms, mood, journal) are encrypted on the device (AES-256) before they sync. A few details needed for reminders and syncing are stored in readable form; section 4 of the privacy policy lists them. In standard mode your key is also backed up on the server so we can help you after a forgotten password. We therefore do not promise that access by us is technically impossible in this mode. In Maximum Privacy mode only you can unlock the key, with your password or your recovery key. Account and subscription data such as your email address are not encrypted this way.

Source: Privacy policy, sections 1 and 4 (own statement)

Other services

Sofía, the optional AI companion, runs on AWS Bedrock with an EU profile, so processing stays within the EU. Sofía includes the chat, AI tips and the daily summary on the home screen, which loads automatically; under “Settings → Sofía & AI” you can turn off Sofía’s personalised AI features. For the daily summary the model receives selected details such as cycle phase, frequent symptoms and moods, contraception details, health averages and hormone values. In the chat, the AI model receives what you write to her in plain text, together with up to five previous messages of the conversation, plus details such as your cycle phase, symptoms from the last two weeks, conditions you have entered, sleep averages and individual measurements such as hormone values. It does not receive the name, email address or journal text from your account. A filter removes recognised email addresses, phone numbers and IBANs from your message; other personal details can remain in the text. Your chat history stays encrypted on your device. Our server stores no conversation content, only a pseudonymised audit record without health details, deleted after 90 days. Crash reports from the app go to Sentry, processed in an EU region; this is switched on by default and can be turned off in the settings, effective from the next app launch. Our list of processors identifies RevenueCat (pseudonymous subscription ID and subscription status) and OpenAI (search term or recipe name for images) as services with a US connection, with no health data included in these transfers. Apple and Google may also be involved in sign-in and payment. They process payments as independent controllers under their own privacy policies.

Source: List of processors, Privacy policy (own statement)

Tracker report

Exodus Privacy found the code signature of one tracker in Android version 1.3.1 (report of July 30, 2026): Sentry for crash reporting. It found no advertising tracker signature, and none of the 23 permissions is for the advertising ID. Exodus only tests Android apps and only recognises known signatures.

Source: Exodus report (independent measurement)

Business model

Subscriptions and one-time passes. No advertising, no data sales.

Source: Fact sheet (own statement)

Export and deletion

Under “My space → Download My Data” you can download your data as a JSON file; you delete your account in the settings. Our privacy policy explains how long residual copies in technical backups, consent records and documents we are legally required to keep are retained.

Source: Privacy policy (own statement)

What Luna is built for

Luna offers features for cycle and period tracking, pregnancy, postpartum and breastfeeding, perimenopause and menopause. It also lets you document fertility treatment (Luna Plus). With your account, your entries are synced between your devices, on iOS and Android.

Luna is an app by icoso consulting S.L. in Santander, Spain. In the UK App Store it is listed as “Luna Cycle to Menopause”: App Store · Google Play

What Luna is not

Common questions

Which period tracker stores my data in the EU?

Luna, for example: synced entries are stored on servers in the EU, and so are the backups; tracking and journal entries are encrypted there, apart from a few details needed for reminders and syncing. For other apps, the privacy policy and the list of processors name the storage location. Even an app without a server of its own can end up with data in the cloud, for example through device backups.

Does Luna store my cycle data in the US?

No. Your synced entries and their backups are stored on servers in the EU, and Sofía is processed within the EU. Our list of processors identifies RevenueCat (pseudonymous subscription ID and subscription status) and OpenAI (search term or recipe name for images) as services with a US connection, with no health data included in these transfers. Apple and Google may also be involved in sign-in and payment. They process payments as independent controllers under their own privacy policies.

Who holds the key to my entries?

In standard mode your key is also backed up on the server so we can help you after a forgotten password; we do not promise that access by us is technically impossible in this mode. In Maximum Privacy mode only you can unlock the key, with your password or your recovery key. Without your password or recovery key, we cannot restore your encrypted entries in this mode.

Does Luna sell my data?

No. Luna is funded by subscriptions and one-time passes, with no advertising and no data sales; that is our own statement. Exodus also found no advertising tracker signature in the Android app.