Privacy Policy

Effective date: 2026-11-15

1. Who we are

This policy explains how 타이디아(Tidia) ("we", "us"), the developer of the LessonDot app for Android and the web (the "app"), handles personal information.

• Developer: 타이디아(Tidia) (representative: 방준환)
• Contact and privacy officer: 방준환 (representative), hello@tidia.app

The app is a tool for instructors who run their own lessons. In this policy "you" means the person using the app.

2. Information you enter in the app

• On Android this data is excluded from the operating system's cloud backup and device-to-device transfer. If you lose the device, the only way to get the data back is the optional backup in section 3. The app warns you while no backup is connected.
• The database on your device is protected by your device and browser (app sandbox, device encryption); the app does not encrypt it separately. Anyone who can use your device can open the app, so erase the data when you use a shared device.
• The app has no fields for sensitive information or national identification numbers. Please do not write such information in free-text notes.
• When you enter information about other people (your students and their guardians), you decide why and how it is used, and you are responsible for handling it lawfully, for example telling them what you record and getting a guardian's consent for a child where the law requires it. See the Terms of Use.

3. Optional backup to your Google Drive

• In this version, Google Drive is the only backup storage offered. The app cannot connect to Microsoft OneDrive.
• The app never reads or writes files outside its own folder. Copies are encrypted on your device before upload, so Google cannot read them. Backups are recovered with the storage account: the recovery information is in the same folder, so anyone who can sign in to that storage account can in principle open the backup. The app tells you this.
• To check a Google connection, the app sends the token it received to Google's token information endpoint to confirm its permissions and who it was issued to.
• On the web, connecting Google Drive runs Google's sign-in script (Google Identity Services) on the app page.
• LessonDot's use and transfer of information received from Google APIs adheres to the Google API Services User Data Policy, including the Limited Use requirements. The app uses Google Drive access only to store and read its own encrypted backup, never shows it to us, and never uses it for ads.
• Google handles your account under its own privacy policy. We have no access to your storage account.

4. Ads and consent

The Android app shows one banner ad at the bottom of the screen from Google AdMob. Where the web app shows ads, they come from Google AdSense. There are no ads on the first-run, restore, backup, error and confirmation screens.

• Ad requests never contain what you entered in the app. The app adds no keywords, screen content or page addresses to ad requests.
• In the European Economic Area, the United Kingdom and Switzerland, the app shows Google's consent form after it first opens and requests no ads until that step is done. In US states with privacy laws, Google's message lets you opt out of the sale or sharing of personal information.
• You can review or change your choice at any time in Settings → Privacy choices (shown where your region has such choices). On Android you can also delete or reset your advertising ID, or turn off ad personalization, in your device settings (usually Settings → Privacy → Ads, or Google → Ads).
• If you refuse personalized ads, the app works the same; you may see non-personalized ads.
• We receive only aggregated ad revenue reports from Google, not information that identifies you.
• To learn how Google uses information from apps that use its services, see Google's page "How Google uses information from sites or apps that use our services" at policies.google.com.

5. Ad-free subscription (Android only)

• In the Android app you can buy a subscription that removes ads. It applies only to the Android app; the web app always shows ads.
• Google Play processes the payment and handles your Google account, payment method and purchase history under Google's policies. The app passes only the subscription product and the plan you chose to Google Play.
• To decide whether to show ads, the app asks Google Play for this account's purchases when it opens, when it comes back to the foreground, and when you tap "Restore purchase". The subscription status is not sent to other devices or to your backup.
• The app stores one value on the device: when Google Play last confirmed an active subscription. If Google Play cannot be reached, the app keeps ads off for up to 38 days from that time. It is not part of your lesson data, backup or exports, and it is deleted as soon as Google Play reports no subscription.
• We do not receive your card number or other payment details. In the Google Play Console we can see order records that Google shows to developers (such as order number, product, price and country). Google keeps them under its policies.

6. Opening the web app

• The web app is served from a static file host, Cloudflare. Like any web server, it may process connection data (IP address, time, requested address, browser information) to deliver and protect the site. We do not use these records to identify you.
• App files and the Korean and Latin fonts come from the same address. When the web app first needs Japanese, Chinese or Vietnamese characters or emoji, it downloads those font files from Google Fonts (fonts.gstatic.com) and keeps them on the device. Google then receives the IP address and browser information of an ordinary web request, but no app data.
• The web app is technically blocked (by a content security policy) from contacting any other server, except the Google addresses needed for the backup and, where the web app shows ads, Google's ad addresses.
• Google Play handles installing and updating the Android app.

7. When you contact us

• If you email hello@tidia.app, we receive your email address, your message and anything you attach.
• Purpose: answering your question, fixing problems and keeping a record of the request.
• We keep support emails for one year after the request is resolved, then delete them, unless the law requires us to keep them longer or you ask us to delete them earlier.
• Please do not send student information, recovery phrases or screenshots that show them. We do not need them to help you.

8. What we, the developer, receive

Nothing else. The app sends nothing to us.

9. Exports and sharing you start

Information leaves the app this way only when you start it, and you choose where it goes: saving the monthly payments CSV file, sending a student summary through your device's share sheet, opening your phone, messaging or email app for a contact, and importing students from a spreadsheet (read on the device only). What you send is then handled by the app or person who receives it; we cannot recall or delete it.

10. Automatically collected information, cookies and device storage

• The app itself sets no cookies and collects no analytics or crash reports.
• The app stores on your device: the lesson database, settings such as theme and first-run state, the backup connection state, the last subscription check (Android) and the ad consent choices (kept by Google's consent software). All of these stay on your device.
• Google's ad software uses the advertising ID (Android) and cookies or similar identifiers (web) as described in section 4. You can refuse personalized ads through Settings → Privacy choices and your device's ad settings, and block or delete cookies in your browser.

11. How long information is kept and how to delete it

• On your device: until you delete it. Settings → Data on this device → Erase data on this device erases the lesson data, the sync keys and the backup connection. Uninstalling the app or clearing the site data in your browser also erases it. We cannot erase it remotely.
• Backup copy: erasing the device data or disconnecting the backup does not delete the copy in Google Drive. To delete it, remove the app's hidden data in Google Drive (on the web: Settings → Manage apps → LessonDot → Options → Delete hidden app data).
• Disconnecting does not revoke the app's permission on the Google side, because your other devices may still use it. You can revoke it in your Google account settings.
• There is no account to delete.
• Support emails: see section 7. Ad data held by Google: see Google's privacy policy.

12. Sharing, service providers and international transfers

• We do not sell personal information for money, and we never receive your lesson data, so we cannot share it.
• Companies involved in running the app: Google (ads and consent, Google Play billing, Google Drive and sign-in, fallback fonts) and Cloudflare (web hosting). Each handles information under its own policies, and may process it in the United States and other countries.

13. Security

• Backup copies are encrypted on your device before upload, and the keys are kept in the platform key store (Android Keystore, or a non-extractable browser key).
• For storage, the app asks only for access to its own folder.
• The web app's content security policy blocks requests to addresses that are not allowed.
• Tokens, keys, recovery phrases, phone numbers, account numbers and names are never written to logs or given to the ad or payment software.

14. Children

The app is a business tool for adults who run lessons and is not directed at children. We do not knowingly collect personal information from children. If you are an instructor and enter information about a child student, that information stays on your device; obtaining a parent's or guardian's consent where the law requires it is your responsibility. A "guardian" contact in the app does not prove that the person is the child's legal representative.

15. Your rights

• You can view, correct, export and delete your lesson data in the app at any time.
• For the information we hold (support emails), you can ask us at hello@tidia.app to access, correct or delete it, or to stop processing it. We answer without undue delay.
• For ad data, use Settings → Privacy choices, your device's ad settings, and your Google account settings.
• Students and guardians: your information is only on your instructor's device and backup. Please ask your instructor to view, correct or delete it.

More rights may apply where you live; see section 17.

16. Changes to this policy

We announce changes on this page and in the app at least 7 days before they take effect, and at least 30 days before for changes that significantly affect your rights.

17. Regional information

A. European Economic Area, United Kingdom and Switzerland

• Controller: 타이디아(Tidia) (hello@tidia.app) for support emails and for the collection of ad data through the ad software in the app (together with Google, which then acts as an independent controller for its ad processing). For lesson data you enter, you are the controller; we do not process it.
• Legal bases: consent for personalized ads and for accessing or storing identifiers on your device (Article 6(1)(a) GDPR, and the ePrivacy rules); performance of a contract for the subscription and for answering your requests (Article 6(1)(b)); our legitimate interests in keeping the website and app secure and in keeping support records (Article 6(1)(f)).
• Your rights: access, rectification, erasure, restriction, data portability, objection, and withdrawing consent at any time (Settings → Privacy choices) without affecting earlier processing. Write to hello@tidia.app.
• Complaints: you can lodge a complaint with the data protection authority where you live or work (in the UK, the Information Commissioner's Office).
• Transfers: Google and Cloudflare may process information outside your country, including in the United States, relying on safeguards such as the EU–U.S. Data Privacy Framework (and its UK and Swiss extensions) or Standard Contractual Clauses.

B. Republic of Korea

Korean users can find the items required by the Personal Information Protection Act (processing purposes, items, retention, transfers abroad, behavioral information, the privacy officer and remedies) in the Korean version of this policy, which is the governing version for users in Korea.

C. United States (California and other states)

• Categories collected in the last 12 months: identifiers (advertising ID, cookies, IP address), internet or other electronic activity (ad views and taps), commercial information (subscription purchases, processed by Google Play) and the content of support emails. We collect no sensitive personal information, and lesson data never reaches us.
• Sources and purposes: your device, through the ad and payment software, and you, when you email us; for the purposes in sections 4, 5 and 7.
• Sale and sharing: we do not sell personal information for money. When you allow personalized ads, Google's collection of identifiers and ad activity through the app may count as "selling" or "sharing" for cross-context behavioral advertising under some state laws. You can opt out with the "Do Not Sell or Share" choice in Settings → Privacy choices and by turning off ad personalization in your device settings; you will then see non-personalized ads. We do not knowingly sell or share personal information of consumers under 16.
• Your rights: to know, access, correct and delete personal information, to opt out of sale or sharing, and not to be discriminated against for using these rights. Send requests to hello@tidia.app; we may need to verify the request, and an authorized agent may act for you.
• Retention: as stated in sections 4, 5, 7 and 11.

18. Contact

타이디아(Tidia) · privacy officer 방준환 · hello@tidia.app

This English version and the Korean version are both official. If they differ, the Korean version applies to users in Korea and the English version to everyone else.