Terms of Use
Last updated: 12 October 2026
These terms apply to the BookCat app and its services, made by Lev Litvak, an individual developer ("we", "us"). They supplement Apple's Licensed Application End User License Agreement (the "Standard EULA"), which also applies. If the two conflict, the Standard EULA prevails. By using BookCat you agree to both.
The app
BookCat is a reader for EPUB and FB2 files that you already have. Reading, importing, your shelf, the vocabulary, review, listening, statistics and sync are free. You are responsible for having the right to read the files you import.
BookCat is an unofficial app. It is not affiliated with, endorsed by or connected to Archive of Our Own (AO3) or the Organization for Transformative Works. Works on AO3 belong to their authors.
AI answers
Smart features are answered by an AI model (OpenAI). Answers are generated automatically and can be incomplete, inaccurate or wrong — including meanings, translations, recaps and descriptions of characters. Don't rely on them where accuracy matters. The text you ask about is sent to OpenAI only with your permission; see the Privacy Policy.
You agree not to use the AI features to break the law, to infringe others' rights, to attack or overload the service, or to get around allowances and limits (for example, by automating requests or tampering with the app).
Free allowance
Every reader gets a one-time free allowance of AI answers, shared by all devices signed in to the same iCloud account. Its size is shown in the app. It doesn't renew.
Subscription
BookCat Pro is an auto-renewing subscription sold through the App Store, monthly or yearly. The price is shown in the app before you buy and is charged to your Apple Account.
- It is not unlimited. It includes a monthly allowance of AI answers, measured in units of the model's work: about 7,500 word lookups or about 3,000 pages of live translation a month. On the yearly plan, the allowance renews monthly from the day of purchase. When it's used up, AI answers stop until it renews; everything free keeps working, and so does your own API key.
- Free trial. The yearly plan may include a 7-day free trial with a smaller allowance, shown in the app. Unless you cancel at least 24 hours before the trial ends, the subscription starts and is charged at the end of the trial.
- Renewal and cancellation. The subscription renews automatically unless you turn it off at least 24 hours before the end of the current period. You can manage or cancel it in your Apple Account settings. Cancelling stops the next renewal; the current period continues until it ends.
- Refunds are handled by Apple under its policies.
We may change the allowance or prices for future periods. A price increase is announced in advance as the App Store requires.
Your own API key
You can enter your own OpenAI API key. Then questions go directly to OpenAI under your account, without our allowance; OpenAI's terms and charges for your account apply, and you're responsible for them.
Availability
We work to keep the service running, but it's provided "as is" and may be interrupted, changed or discontinued. To the extent permitted by law, we're not liable for indirect damages or for the content of AI answers.
Changes
If these terms change, the new version will be posted here with a new date. Continuing to use BookCat after a change means you accept it.