Lotang is an educational wellness app. It is not a medical device and does not diagnose, treat, cure, or prevent any disease. Always consult a qualified clinician before making health decisions.
Data controller: Abas Haşimoğlu, Başakşehir Çam ve Sakura Şehir Hastanesi, Başakşehir Mah. Şehir Hastanesi Cad. No: 2L, Başakşehir / İstanbul, Türkiye. Contact: support@lotang.app.
The short version
- Your tongue photograph is analysed entirely on your device. The image itself is not uploaded to our servers. What travels is a small set of derived observations: colour, coating, shape, moisture; never the picture.
- No artificial intelligence is involved. Your reading is produced by Lotang's own deterministic engine. Your data is not sent to any third-party AI service and is never used to train any model.
- We do not sell your data. We do not use it for advertising, and we do not track you across other companies' apps or websites.
What stays on your device
- Your tongue photographs, at full resolution.
- Your onboarding answers, profiles, past readings and streak history, cached locally so the app works without a connection.
You can remove local data at any time from within the app (delete a reading, or Settings → Account).
What we store on our servers
Lotang uses Supabase (hosted in the United Kingdom (London)) as its backend. The following is associated with your account so your readings and profiles are consistent across sessions and devices:
| Data | Why |
|---|---|
| An anonymous account identifier, created automatically the first time you open the app | So your readings belong to you before you ever sign in |
| Derived tongue observations: colour, coating, shape, moisture, texture, regional distribution, computed on your device | To generate the reading. Never the photograph itself. |
| Your reading results: pattern, organ picture, element scores, suggestions | So you can re-open past letters and see trends |
| Profile details you enter: name or nickname, relationship, age, gender, height, weight; for yourself and any loved ones you add | To personalise readings and keep household profiles apart |
| Your onboarding and differential answers, and any symptoms you choose to add, which may include information about conditions, medications or allergies you volunteer | To refine the reading and filter food and herb suggestions |
| Your subscription tier and status | To unlock features and enforce daily reading limits |
| A profile avatar photograph, only if you choose to set one | To show a face on the profile card. Stored in a private bucket, readable only through short-lived signed links issued to your account |
Everything is transmitted over an encrypted (TLS) connection and protected by row-level security so that one account cannot read another's rows.
We do not collect your contacts, your location, your advertising identifier, or your browsing behaviour.
Account and authentication
Lotang begins with an anonymous account, so you can use it without giving us any identifying information. If you later sign in (for example with Sign in with Apple or Google), we store the authentication identifier provided by that service so your readings and subscription follow your account. We never receive or store your password.
Subscriptions and payments
Subscriptions are sold by Apple or Google and administered through RevenueCat. We never see or store your payment card details. We receive only your subscription state: active, expired, plan tier, and whether you qualify for Founder Member status, so the right features unlock.
Their handling of your data is governed by their own policies:
- Apple: apple.com/legal/privacy
- Google: policies.google.com/privacy
- RevenueCat: revenuecat.com/privacy
Health-related information
Tongue observations, symptoms and any conditions you volunteer relate to your wellbeing, and we treat them as sensitive. We do not use them for advertising, marketing, profiling or data mining, and we do not disclose them to third parties except to the infrastructure providers needed to run the service (see above) or where the law requires it.
Where the GDPR applies, our lawful basis for processing this category of data is your explicit consent, given when you submit a reading. You may withdraw it at any time by deleting your account.
Retention and deletion
- Photographs: your tongue photographs are held on your device until you delete the reading or clear local data. They are not stored on our servers.
- Server-side data: retained while your account exists.
- Deletion: Settings → Account → Delete Account permanently removes your server-side readings, profiles, avatars and subscription record, and signs you out. This cannot be undone.
- You may also write to support@lotang.app to request access to, correction of, or deletion of your data.
Your rights
Depending on where you live, you may have the right to access, correct, export, restrict or delete your personal data, to object to processing, and to lodge a complaint with your local data protection authority. Write to support@lotang.app and we will respond within the period your law requires.
Tracking
Lotang does not track you across other companies' apps or websites, does not use advertising SDKs, and does not sell or share personal information for cross-context behavioural advertising.
Children
Lotang is not directed to children under 13 (or the minimum age of digital consent where you live). We do not knowingly collect data from children. If you believe a child has provided us with data, write to support@lotang.app and we will delete it.
International transfers
Our infrastructure providers may process data in countries other than yours. Where required, such transfers rely on the European Commission's Standard Contractual Clauses or an equivalent safeguard.
Changes
We may update this policy. Material changes will be reflected in the "Last updated" date above and, where appropriate, surfaced in the app.
Contact
Abas Haşimoğlu · Başakşehir Çam ve Sakura Şehir Hastanesi, Başakşehir Mah. Şehir Hastanesi Cad. No: 2L, Başakşehir / İstanbul · Türkiye