Underline Privacy Policy

01Information we collect

Depending on how you use the App, we may collect:

• Your library: books, quotes, notes, tags, favorites, book covers and reminder settings. These are stored only on your device; we never receive them. Backup and export files (.underline, CSV, Markdown, PDF) stay wherever you choose to save or share them.
• Camera and photos: page photos, scans and book barcodes are read on your device (Apple's Vision framework on iOS, Google ML Kit on Android). Images are not uploaded, and a page photo is not kept once you have chosen your lines.
• Book searches: the title, author or ISBN you search for is sent to Open Library and Google Books to find the book and its cover. As with any internet request, your IP address is visible to them; no account or identifier from the App is attached.
• Purchase data processed by RevenueCat: a random app user ID created on your device (not linked to your name or email) and your Underline Pro purchases and subscription status. Payment details are handled by Apple or Google; we never see them.
• Advertising data processed by Google AdMob for users without Underline Pro: device and advertising identifiers (on iOS only if you allow tracking), IP address, approximate location derived from it, ad interactions and diagnostics. Your books and quotes are never shared with advertisers.

We do not collect your name, contact details, precise location, contacts, photos or other sensitive information unless the App explicitly asks for it and you choose to provide it.

02How we use information

• To provide, maintain and improve the App
• To show ads that keep the App free
• To unlock and restore the features you purchase
• To respond to your support requests

We never sell your personal information and do not use it for any other purpose.

03Third-party services

The App uses the following third-party services, which may collect information as described in their own privacy policies:

• Open Library (Internet Archive): looking up books and their covers (the request contains your search or ISBN and your IP address, nothing else)
  archive.org/about/terms
• Google Books API: looking up books and their covers (the request contains your search or ISBN and your IP address, nothing else)
  policies.google.com/privacy
• Google ML Kit (Android): recognizing text and barcodes on the device; ML Kit may send Google anonymous usage and performance metrics
  developers.google.com/ml-kit/android-data-disclosure
• Google Fonts: downloading a Japanese or Chinese font once, when you export such a book as a PDF (the request contains your IP address and the font requested, nothing else)
  developers.google.com/fonts/faq/privacy
• RevenueCat: managing in-app purchases and subscriptions
  www.revenuecat.com/privacy
• Google AdMob: showing advertisements
  policies.google.com/privacy

04Advertising

The free version of the App shows ads served by Google AdMob. To show and measure ads, AdMob may use your device's advertising identifier, IP address and information about how you interact with ads. In the EEA, the UK and Switzerland we ask for your consent before ads are personalised, and on iOS the App asks for permission before using the advertising identifier for tracking. If you decline, you may still see non-personalised ads.

• Android: Settings › Google › Ads lets you reset or delete your advertising ID.
• iOS: Settings › Privacy & Security › Tracking lets you turn off tracking for the App.
• Buying Underline Pro removes ads from the App completely.

05Purchases

In-app purchases and subscriptions are processed by Apple (App Store) or Google (Google Play). We do not receive or store your payment card details.

06Data retention and security

Data stored on your device stays there and is removed when you uninstall the App. Information processed by third-party services is retained according to their policies. We use reasonable technical and organisational measures to protect information, but no method of transmission or storage is completely secure.

07Children's privacy

The App is not directed at children under 13 and we do not knowingly collect personal information from them. If you believe a child has given us personal information, contact us and we will delete it.

08Your rights

Depending on where you live (for example under the GDPR or the Turkish Personal Data Protection Law, KVKK), you may have the right to access, correct or delete your personal information, to restrict or object to its processing, and to complain to a data protection authority. To exercise these rights, contact us.

09Changes to this policy

We may update this Privacy Policy from time to time. Changes are posted on this page with a new "Last updated" date. Continued use of the App after changes means you accept the updated policy.

10Contact

If you have any questions about this Privacy Policy, contact us at supportzaustudios@gmail.com.