Privacy Policy

Information you give us. When you sign in, buy, or contact us, we collect your email address and any message you send us. We do not ask you to create a password. If you choose to receive updates, we also keep your email address on our mailing list (see Section 3).

Purchase information. When you buy a problem set, we receive a record of your order, including what you bought, the amount, the date, and a reference from our payment processor. We do not receive or store your full payment card number (see Section 4).

Download and account activity. We record which problem sets you download, when, and from which IP address. We also keep a license ID for each file you download (see Section 5).

Information collected automatically. After you use your sign-in link, we set a cookie that keeps you signed in. We also collect basic technical information, such as your IP address, browser type, and the pages you visit, to run and protect the Services. [ANALYTICS: describe any analytics tools we use, or state that we use none.]

Embedded videos. Our lessons are hosted on YouTube and embedded on our website. YouTube may collect information about your viewing and set its own cookies under its own privacy policy. [LAWYER: consider whether to use YouTube’s privacy-enhanced embed mode.]

We use your information to:

• sign you in and keep your account secure;
• deliver your purchases, license them to you, and send receipts;
• respond to your questions and requests;
• send updates you have chosen to receive;
• prevent fraud, abuse, and unauthorized sharing of our materials;
• maintain and improve the Services; and
• comply with the law.

We do not sell your personal information, and we do not share it for third-party advertising. [LAWYER: confirm this statement against applicable state privacy laws.]

We share information only with service providers who help us operate the Services and who are required to protect it: payment processing (Stripe), email delivery ([EMAIL SERVICE PROVIDER]), website hosting and file storage ([HOSTING PROVIDER]), and [ANALYTICS PROVIDER, if any]. We may also disclose information if the law requires it, to protect the rights, safety, or property of Arithmekit or others, or as part of a merger, acquisition, or sale of our business.

We use your email address to send sign-in links, receipts, and other messages needed to provide the Services. We send newsletters and promotional email (“marketing email”) only if you opt in.

Opting in is optional, and the box is never pre-checked. After you opt in, we send a confirmation email, and you are added to our list only when you click the link in it. We record when and how you gave your consent.

Every marketing email includes a link to unsubscribe in one click, and you can also change your preference in your account. After you unsubscribe, we stop sending marketing email, but we may still send messages needed to provide the Services, such as receipts and sign-in links. Our mailing address is [BUSINESS MAILING ADDRESS]. We do not sell or rent our mailing list.

Payments are processed by Stripe, Inc. When you pay, you enter your card details on a page hosted by Stripe. We do not see or store your full card number. Stripe collects and uses your payment information under its own privacy policy and terms.

We receive confirmation of your payment and limited order details from Stripe. [LAWYER: confirm exactly which details Stripe shares with us, and how sales tax is handled at checkout.]

Each problem set you download is prepared just for you. It includes your email address and a license ID in the footer of every page and in the file’s hidden properties. This marks your copy as licensed to you and helps protect our work, so that we can keep creating and sharing high-quality problem sets. We keep a record that links each license ID to your account so that we can confirm your license and, if a file is ever shared without permission, trace it back to its source.

If we find unauthorized sharing, we may suspend your account and take other steps allowed by our Terms of Use and the law.

Account controls. When you are signed in, you can download a copy of your data, change your email preferences, and delete your account. You can unsubscribe from marketing email at any time. Deleting your account removes your account, sign-in and download records, and mailing list entry. We keep order records, without identifying links where possible, as needed for tax, accounting, and legal purposes. [LAWYER: confirm retention periods.]

Privacy rights. Depending on where you live, you may have the right to access, correct, delete, or receive a copy of your personal information, to opt out of certain uses, and to not be treated differently for using these rights. If you are in the European Economic Area, the United Kingdom, or Switzerland, you may also object to or restrict our processing and complain to your data protection authority. [LAWYER: confirm which laws apply, our legal bases for processing, and rules for international transfers.] To make a request, email [SUPPORT EMAIL]. We may need to verify your identity first.

Retention and security. We keep personal information only as long as we need it for the purposes above or as the law requires. We use reasonable safeguards, such as encrypted connections, hashed sign-in tokens, and limited access, but no system is completely secure.

For questions or requests about this policy, contact us at [SUPPORT EMAIL] or [BUSINESS MAILING ADDRESS].

We may update this policy from time to time. We will post the new version here with a new “Last updated” date and, if the changes are significant, tell you by email or on the Services.