Professor Euler

Terms of service

Last updated: 18 October 2026

These terms are between you and David Schmid, the maker of Professor Euler (“the app”). Contact: ai.professor.euler@gmail.com. By installing or using the app you agree to these terms and to the privacy policy. The same privacy policy is published at https://github.com/dawei7/professor-euler-privacy/blob/main/PRIVACY_POLICY.md.

Who the app is for

Professor Euler is a free, non-commercial mathematics study app for adults aged 18 and older. It is not a school, a university, or a credential. It is not directed at children. If you are under 18, do not use it.

What you receive

You receive a personal, non-exclusive, revocable permission to use the app on your own Android devices and Windows computers. There is no app subscription and no charge from David for the app itself. That permission does not transfer the copyright in the software, the textbooks, the illustrations, or the name Professor Euler.

The app includes mathematics books and course resources that can legally be shared, each under its own license. Those licenses, not these terms, decide what you may do with a particular book. Do not remove license notices or redistribute a book beyond what its license allows.

Books you import

My books lets you open PDFs and prepared book bundles that you supply. You are responsible for having the right to use those files. The app stores them on your device so that a book which cannot be redistributed is not shipped inside the app.

Your study work

Notes, handwriting, drawings, and other study files you create remain yours. You decide when to export them, share them, send them to an AI provider, or turn on sync. Do not put another person’s private information into the app unless you have a proper basis to do so.

AI providers

Reading and handwriting work without an AI connection. Check and Ask Euler use a provider you choose and a key you supply: Google Gemini, DeepSeek, OpenRouter, or DeepInfra. You pay that provider under its own terms. David does not sell AI access and does not operate the grading service.

AI output can be wrong, incomplete, or too generous. It is not a grade from an institution and not a proof that a solution is correct. You judge the mathematics yourself.

Optional Google sign-in

Sync is off until you turn it on for a profile and complete Google’s sign-in page. The app then asks only for a hidden folder in your own Google Drive and for the email address of that Google account. It does not ask for the rest of your Drive. You can turn sync off, disconnect inside the app, or remove the app’s access from your Google Account. Google’s terms apply to that account. Details are in the privacy policy.

Acceptable use

Use the app for your own study. Do not misuse it to break the law, to infringe copyright, to probe or disrupt the app or the reporting service, or to send API keys or other people’s secrets in a feedback message or an AI report.

The app can change or stop

The app, the book list, and these terms can change. A change to these terms will show a new date on this page. If you keep using the app after that date, the new terms apply. David may stop offering the app or a particular book. Study files on your device are your copy to keep; keep a backup of work you cannot lose. No device or service can promise permanent storage.

No warranty

The app is provided as it is and as it is available. David does not warrant that it will be uninterrupted, that every exercise is perfectly marked, that an AI answer is true, or that a book file is free of error. Rights that cannot be excluded under the law that applies to you remain in force.

Liability

To the extent the law allows, David is not liable for lost study work, provider charges, incorrect AI feedback, or other indirect or consequential loss arising from use of the app. Nothing in these terms limits liability that cannot legally be limited, including liability for intent or gross negligence where the law forbids that limit.

Law

These terms are governed by the laws of Switzerland, excluding conflict-of-law rules. Where you have a mandatory right to bring a claim in the courts of your home country, that right is unchanged.

Contact

David Schmid · ai.professor.euler@gmail.com · Switzerland