Last updated · July 2, 2026

Terms of Use

These terms are the agreement between you and us for using the Kern iOS app and the kern.cards website. Please read them before using Kern.

1. Who we are and what these terms cover

Kern (the app) and kern.cards (the website), together the "Service", are operated by Quantum IT d.o.o., Bana Tome Erdodyja Bakaca 2, 34000 Pozega, Croatia ("Quantum IT", "we", "us", "our").

By downloading, installing, or using the Service, you agree to these Terms of Use and to our Privacy Policy, which explains how we handle data. If you do not agree, do not use the Service.

2. Who may use Kern

You must be at least 13 years old to use the Service. If the laws of your country require a higher minimum age to consent to digital services, you must meet that age or have your parent's or guardian's permission.

3. What Kern is (and is not)

Kern creates original, paraphrased study cards about the key ideas of books you tell us you have read, and schedules those cards for review so the ideas stay with you.

• Cards are our own paraphrases, generated from general knowledge about a book. They are not excerpts, quotations, or reproductions of a book's text.
• Cards are not a substitute for a book. Kern is a memory aid for books you have already read, not a summary service.
• Kern is not affiliated with, endorsed by, or sponsored by any author or publisher. Book titles and author names appear in Kern only to identify which book a card belongs to, and all trademarks remain the property of their respective owners.

4. AI-generated content

Cards are generated by an artificial intelligence model. They may occasionally be incomplete, outdated, or inaccurate, and may express an idea differently than the book's author would. For some books the model may not be able to produce a deck at all.

The Service is provided for personal learning. Nothing in Kern is professional, medical, legal, financial, or investment advice. Do not rely on a card for decisions that matter without checking a primary source.

5. Your license to use Kern

We grant you a personal, non-exclusive, non-transferable, revocable license to install and use the app on Apple devices you own or control, and to use the cards within the app for personal, non-commercial study. The Service, including the app, the website, and the generated cards, is owned by us or our licensors and is protected by intellectual property laws. We reserve all rights not expressly granted to you.

6. Acceptable use

You agree not to:

• copy, scrape, bulk-export, republish, sell, or redistribute cards or decks outside the app;
• use the Service or its output to build a dataset or a competing product;
• reverse engineer, decompile, or modify the app, except to the extent the law expressly permits;
• circumvent purchase requirements, generation limits, or other technical protections;
• interfere with or disrupt the Service or its infrastructure; or
• use the Service for anything unlawful.

7. Free books, subscriptions, and purchases

Free tier

Kern is free for your first two books. After that, adding more books requires Kern Plus or a single-book purchase.

Kern Plus subscription

• Kern Plus is an auto-renewing subscription, offered monthly or yearly. Current prices are always shown in the app before you buy.
• Payment is charged to your Apple ID account when you confirm the purchase.
• The subscription renews automatically unless you cancel at least 24 hours before the end of the current period. Your account is charged for renewal within 24 hours before the period ends.
• You can manage or cancel your subscription in your App Store account settings at any time. Deleting the app does not cancel a subscription.
• If we change subscription prices, the change applies from your next renewal, with notice as required by App Store rules, and you can cancel before it takes effect.

Single-book purchases

You can also unlock an individual book with a one-time purchase. A single-book unlock applies to that book only and is tied to your Apple ID and iCloud account.

Billing, refunds, and restoring

All billing and payment processing is handled by Apple under Apple's own terms; we never receive your payment details. Refunds are governed by Apple's refund policy, and refund requests should be made to Apple (for example at reportaproblem.apple.com). Except where the law requires otherwise, payments are non-refundable by us. If you reinstall Kern or switch devices, use Restore Purchases in Settings to bring back what you own.

8. Availability and changes to the Service

Generating cards requires an internet connection; reviewing already generated cards works offline. We may add, change, or remove features, apply fair-use limits to card generation, or discontinue the Service, with reasonable notice where the law requires it. We work to keep the Service available but cannot guarantee it will be uninterrupted or error-free.

9. Feedback

If you send us feedback, ideas, or suggestions, you grant us a perpetual, irrevocable, royalty-free, worldwide license to use them without restriction or obligation to you.

10. Termination

You can stop using Kern at any time by deleting the app. We may suspend or terminate your access to the Service, without prior notice, if you breach these Terms, abuse the Service, or where we are required to by law. Sections of these Terms that by their nature should survive termination (including intellectual property, disclaimers, and limitation of liability) survive it.

11. Disclaimers

The Service is provided "as is" and "as available", without warranties of any kind, whether express, implied, or statutory, including implied warranties of merchantability, fitness for a particular purpose, and non-infringement, to the maximum extent permitted by applicable law. We do not warrant that the Service will meet your requirements, be accurate, or operate without interruption.

Some jurisdictions do not allow the exclusion of certain warranties, so parts of this section may not apply to you. If you are a consumer, nothing in these Terms limits the statutory warranties and guarantees you are entitled to under the law of your country.

12. Limitation of liability

To the maximum extent permitted by applicable law, we will not be liable for any indirect, incidental, special, or consequential damages, or for loss of profits, data, or goodwill, arising out of or related to your use of the Service. Our total liability for all claims relating to the Service is limited to the greater of the amount you paid us through the Service in the 12 months before the claim arose and 100 EUR.

Nothing in these Terms excludes or limits liability that cannot be excluded or limited under applicable law, including liability for intent or gross negligence, or for death or personal injury caused by negligence.

13. Consumers in the European Union

If you are a consumer in the European Union, you benefit from all mandatory provisions of the consumer protection law of the country where you live, and nothing in these Terms takes those protections away. Statutory rights of withdrawal for digital content purchased through the App Store are handled through Apple in accordance with its terms.

14. Apple App Store terms

Because Kern is distributed through Apple's App Store, the following also applies:

• These Terms are between you and Quantum IT only, not with Apple. Apple is not responsible for the Service or its content.
• Apple has no obligation to provide maintenance or support for the app.
• In the event the app fails to conform to an applicable warranty, you may notify Apple and Apple will refund the purchase price of the app to you (if any); to the maximum extent permitted by law, Apple has no other warranty obligation with respect to the app.
• Apple is not responsible for addressing any claims relating to the app, including product liability claims, claims that the app fails to conform to legal or regulatory requirements, and claims under consumer protection or similar legislation.
• Apple and its subsidiaries are third-party beneficiaries of these Terms and may enforce them against you.
• You represent that you are not located in a country subject to a U.S. government embargo or designated as a "terrorist supporting" country, and that you are not on any U.S. government list of prohibited or restricted parties.
• Your use of the app must also comply with Apple's Media Services Terms and Conditions.

15. Governing law and disputes

These Terms are governed by the laws of Croatia, excluding its conflict-of-law rules. If you are a consumer in the European Union, you also benefit from the mandatory provisions of the law of your country of residence and may bring proceedings in the courts of that country.

If you have a concern or dispute, please contact us first at hello@kern.cards; most issues can be resolved informally and quickly.

16. Changes to these Terms

We may revise these Terms from time to time. If a change is material, we will give reasonable notice in the app or on the website before it takes effect. By continuing to use the Service after a revision becomes effective, you agree to the revised Terms. If you do not agree, stop using the Service.

17. Other provisions

• Severability. If any provision of these Terms is held unenforceable, it will be modified to the minimum extent necessary and the rest remains in effect.
• Waiver. Our failure to enforce a right under these Terms is not a waiver of that right.
• Entire agreement. These Terms and the Privacy Policy are the entire agreement between you and us regarding the Service.
• Translation. If these Terms are translated, the English version prevails in case of a dispute.

18. Contact

Quantum IT d.o.o.
Bana Tome Erdodyja Bakaca 2
34000 Pozega, Croatia
hello@kern.cards