Lemma Privacy Policy
Lemma (lemmamath.net) is a free competition math practice tool built and run by Justin Puno, an individual based in Carmel, Indiana. This policy explains what information Lemma collects, why, and who can see it. Questions: justintpuno@gmail.com.
The short version
- You can use Lemma without an account. In guest mode we collect no name or email.
- Accounts are optional. They exist so a student can save practice history.
- We do not sell personal information, show advertising, or use student information to build advertising profiles.
- We use a small number of service providers to run the site (listed below).
- You can ask us to delete an account and its saved data at any time.
What we collect
If you use Lemma as a guest
For each practice problem you request, our server records a random device ID (generated in your browser and not linked to your name), the contest, topic, and difficulty you chose, whether the problem came from our stored problem bank or was newly generated, a short referral tag from the link you used to reach us (for example, which school or community shared it), if there was one, and the time. We use this to count how many problems are served and roughly how many devices use Lemma. Your on-screen score and streak stay in your browser page and reset when you reload.
If you create an account
We collect the username, email address, and password you enter. Your email is used to confirm your account and sign you in. Your password is handled by our authentication provider and stored in hashed form; we cannot see it.
If you are signed in: saved practice history
For each problem you answer we save: the contest, topic, difficulty, and round; whether you were correct; how many seconds you took; a random session ID and start time for that visit; the text of the problem, the answer you gave, the correct answer, and the solution; and the time. This powers the "My progress" page, which only the signed-in student can see.
If you send feedback
The message you type is emailed to us through our email provider. It is not stored in our database, but it stays in our inbox until we delete it. Please do not include personal information in feedback.
Collected automatically
Our hosting provider automatically logs standard technical information such as IP address, browser type, and pages requested, for security and reliability. Lemma stores a random device ID, the referral tag from the link you used (if any), and, when you are signed in, your sign-in session in your browser's local storage. Lemma does not use advertising or cross-site tracking cookies. To display math and fonts, pages load files from third-party content delivery networks (Google Fonts, cdnjs, and jsDelivr), which receive your IP address and browser information when your browser requests those files.
How we use information
- To provide practice problems, check answers, and show progress.
- To confirm accounts and respond to feedback and requests.
- To keep Lemma secure and working, and to understand overall usage, such as how many problems are served.
AI-generated problems
Practice problems are written by an AI model from Anthropic. Most are generated ahead of time and stored; some are generated on request. When a problem is generated on request, our server sends Anthropic only the contest, topic, difficulty setting, and the correct/incorrect pattern of the student's last few answers (up to six). We do not send names, emails, account IDs, or the text of student answers.
Who we share information with
We share information only with service providers that help us run Lemma, and only as needed:
| Provider | Purpose | Information involved |
|---|---|---|
| Vercel | Website hosting | IP address, browser information, pages requested |
| Supabase | Database and sign-in | Accounts, saved practice history, anonymous usage logs |
| Resend | Sending email | Email address (confirmation emails); feedback message contents |
| Anthropic | Generating problems | Contest, topic, difficulty, recent correct/incorrect pattern (no personal information) |
| Google (Gmail) | Receiving feedback email | Feedback message contents |
| Google Fonts, cdnjs, jsDelivr | Fonts and code libraries | IP address, browser information |
We may also disclose information if required by law or to protect safety. If a school or district signs a data privacy agreement with us, that agreement's terms apply to data from its students.
Children and schools
Lemma is designed for students in middle school through high school. Accounts are optional. Students under 13 should use Lemma as a guest unless a parent or their school has approved creating an account. We do not knowingly collect a username or email from a child under 13 without that approval. If you believe a child has created an account without it, email us and we will delete it.
Schools and districts may ask us to delete their students' accounts and data at any time.
Where information is stored and how long we keep it
Information is stored with the providers above in the United States; our database is hosted in Oregon. Accounts and saved practice history are kept until you or your school ask us to delete them. Anonymous usage logs contain no name or email and are kept as long as they are useful for understanding how Lemma is used; we may delete or aggregate them at any time.
Security
Lemma is served over HTTPS. In our database, a signed-in student can read only their own saved history, and our server-side access keys are kept secret. No online service is perfectly secure. If we learn of a breach affecting personal information, we will notify affected users and any school or district we have an agreement with, promptly and as the law or agreement requires.
Your choices
- Email us to see or delete your account and saved practice history. We will act within 30 days.
- You can use Lemma without an account.
- You can reset your device ID by clearing Lemma's site data in your browser. This does not stop usage logging.
Changes
We may update this policy. The date at the top shows the latest version. If we make a significant change, we will say so on the site.
Contact
Justin Puno, justintpuno@gmail.com