Privacy Policy
Effective Date: July 29, 2026
Welcome to Tilia ("the App"). Your privacy is important to us. This Privacy Policy explains what information we collect, how we use it, and your rights regarding your information.
Information We Collect
Depending on how you use the App, we may collect:
- Account information, such as your email address or authentication credentials.
- Profile information you choose to provide.
- Books and other content that you upload.
- Information about books you choose to make public.
- Technical information such as device type, operating system version, app version, and IP address.
- Crash and error diagnostics. When the App or our servers encounter a problem, we collect the technical details of that problem: the type of error, where in our code it happened, and the device model, operating system version, and app version it happened on. We have configured this deliberately so that it does not include screenshots of your screen, the contents of your library, the text you are reading, or your vocabulary data.
- Usage information, such as how you interact with the App. We record a small, fixed set of milestones — opening the App, signing up, starting and finishing the vocabulary test, adding a book, reviewing your first flashcard, viewing the subscription screen, and subscribing — so we can see where people get stuck. We have configured this deliberately so that it does not include which books you add, what you read, the words on your flashcards, or your test answers.
How We Use Your Information
We use your information to:
- Provide and operate the App.
- Store and synchronize your library.
- Display books that you choose to make public.
- Improve reliability, security, and performance.
- Respond to support requests.
- Detect abuse, fraud, and violations of our Terms of Service.
Public Content
Books and information that you choose to make public may be visible to other users. Please carefully review your content before making it public.
Content Ownership
You retain ownership of the content that you upload. By uploading content to the App, you grant us a non-exclusive, worldwide license to store, process, display, and distribute your content as necessary to operate the service according to your privacy settings.
Data Sharing
We do not sell your personal information.
We may share information:
- with service providers that help us operate the App;
- when required by law;
- to protect our users, our rights, or the security of the App;
- in connection with a merger, acquisition, or sale of assets.
Third-Party Services
We rely on a small number of outside providers to run the App. Each one receives only what it needs for its stated purpose, and none of them is permitted to use your information for their own purposes.
- Hetzner hosts our servers and stores your library. It holds everything you store in the App.
- Sentry collects crash and error diagnostics. It receives error details, your device model, and your operating system and app version — not your library, what you are reading, or your account identifiers.
- PostHog collects the usage milestones described above. It receives the event name, your account identifier, and your device and app version — not your library, your reading, or your vocabulary data.
- Google Firebase Cloud Messaging delivers push notifications. It receives a device token and the text of the notification.
- RevenueCat manages subscriptions. It receives your account identifier and your purchase status.
- Google and Apple provide sign-in, if you choose to use it. We receive what their sign-in service returns to us, such as your email address and name.
- Resend sends transactional email, such as password-reset codes. It receives your email address and the message.
- Open Library and Google Books supply book covers and descriptions — see the note below.
A note on book covers. When the App shows a cover image, your device currently requests that image directly from Open Library or Google Books. This means those providers can see your device's IP address and which book the cover belongs to. We are changing this so that covers are served from our own servers instead, which will stop that information leaving our systems. We will update this policy when that change ships.
Some of these providers operate outside your country, so your information may be processed elsewhere, including in the United States.
Data Security
We use reasonable administrative, technical, and organizational measures to protect your information. However, no system can guarantee complete security.
Data Retention and Account Deletion
We retain your information as long as necessary to provide the App or comply with legal obligations. If you wish to permanently delete your Tilia account and all associated user data, please email your request to [newtonianianlabs@gmail.com] from the email address you used to register. Deletion requests will be processed within 3 days.
Children's Privacy
The App is not intended for children under the minimum age required by applicable law. We do not knowingly collect personal information from children where prohibited.
Changes to this Policy
We may update this Privacy Policy from time to time. Continued use of the App after changes become effective constitutes acceptance of the updated policy.
Contact
If you have questions about this Privacy Policy, please contact us at:
Email: [newtonianianlabs@gmail.com]