Yohaku 余白

Yohaku Privacy Policy

Effective date: 15 July 2026 · Version: 1.0

This English version is the controlling version of the policy. Translations are provided for convenience.

Yohaku is a self-tracking app for perimenopause and menopause. This policy explains what data the app processes, where it lives, and what happens if you use the optional AI features. It is written to be read in full.

In short (an honest summary; full text below)

  • All your records are stored only on your device. We run no server with your data, no accounts, no analytics, no ads, no trackers.
  • By default the app sends nothing to the internet.
  • The only exception is the optional AI features (subscription): with your explicit consent, your question and the anonymised summaries you select are sent to Anthropic (Claude API). Free-text notes and your profile name are never sent.
  • Deleting your data is entirely in your hands: in the app, or by uninstalling it.

1. Data controller

Data controller: Ivan Chukarev, an independent developer. Privacy contact: support@yohakutrack.com.

2. What data the app processes and where it lives

The app is, at its core, a local diary. You may log: symptoms and their intensity, free-text notes, lifestyle factors (sleep, stress, alcohol, caffeine, sugar, spicy food, exercise), cycle data, medications, a profile name (a pseudonym is fine) and an optional birth year.

All of it is stored in a local database on your device and processed there: statistical correlation analysis, stage estimation, cycle prediction and the doctor PDF report all run on-device, offline.

We technically have no access to this data: no server-side database exists. Android cloud backup is disabled for the app, so your data does not go into Google's backup. Data leaves the device only through actions you take yourself: an export file, a PDF report you choose to share, or the optional AI features (section 3).

3. Optional AI features (subscription)

The AI chat, deep analysis and annual report use the cloud model Claude (Anthropic). These features are off by default and require two explicit actions: a subscription and a separate consent to data transfer.

When used, the following is sent:

Never sent: free-text notes and your profile name. Before sending you can inspect the exact request content — the “Show what will be sent” button.

Transfer path: requests go through our technical proxy (Cloudflare Workers), which does not store request contents and exists only so the API key is not embedded in the app — and on to Anthropic. The proxy runs on infrastructure operated by Cloudflare, Inc. (Cloudflare privacy policy). As with any network request, technical connection data (IP address, request time) is processed in transit; we do not store or use it.

Processing at Anthropic: under the commercial API terms your data is not used to train models; it is retained for up to 30 days for abuse monitoring and then deleted. An honest caveat: requests flagged by Anthropic's automated safety systems may be retained longer under their policy. Anthropic is an independent operator with its own policy: anthropic.com/legal/privacy.

Legal basis. Data is sent to the AI features solely on the basis of your explicit consent (Art. 6(1)(a) and 9(2)(a) GDPR: health data is a special category of personal data). You can withdraw consent at any time in the AI data settings — transfers stop; the rest of the app is unaffected. Withdrawal does not affect the lawfulness of transfers already made.

Transfers outside the EEA. Anthropic and Cloudflare are U.S. companies, so using the AI features involves a transfer of data to the United States. Anthropic relies on the EU Standard Contractual Clauses (SCCs); Cloudflare is certified under the EU-U.S. Data Privacy Framework.

Your AI chat history is stored locally on the device and can be deleted by you at any time.

4. Purchases

Subscriptions are handled by the app store (Google Play / App Store). Payment details are processed by the store; we never receive or store them.

5. Permissions and utilities

6. Security

All network requests made by the app use encrypted connections (TLS). The local database lives in the app's sandboxed storage (Android app sandbox) and is not accessible to other apps; we additionally recommend using a device screen lock. The website yohakutrack.com, where this policy is published, uses no cookies and collects no visitor data.

7. Your rights and control

Because the data lives with you, most rights are exercised directly in the app: access — on the app's screens; portability — JSON export; erasure — selective or full deletion in settings, or by uninstalling the app (data is erased with it). This corresponds to the rights of access, rectification, erasure, restriction and portability. For matters related to AI transfers (e.g. a deletion request on Anthropic's side within their retention window), contact us: support@yohakutrack.com.

If you are in the EU/EEA or the UK, you have the right to lodge a complaint with your national data protection authority. Residents of certain U.S. states may have additional rights under state law — see our Consumer Health Data Privacy Policy and contact us; we will help you exercise them.

8. Children

The app is intended for adults and is not directed at persons under 16.

9. Medical disclaimer

Yohaku is not a medical device, does not diagnose, and does not replace professional medical advice. All observations and estimates are aids for self-tracking and for a conversation with a clinician.

10. Changes to this policy

If this policy changes, we will update this page and the effective date; material changes will be announced in the app. Previous versions are available on request.