App privacy policy
Last updated October 30, 2026.
This policy covers the Sanmaru iPhone app. OtterVolt Labs LLC runs the app and is responsible for the data described here. The website and its Android waitlist have their own notice.
What we collect
- Your account. An account ID, and the email address and name that Sign in with Apple or Google shares with us.
- Your study profile. Birth year (never a full date of birth), country, language, time zone, grade, textbooks, and review settings.
- What you add. Photos of problems, the text and math read from them, the tags and notes you keep, your review history, and your test dates. The app looks for faces in a photo and blurs them before the photo leaves your device.
- Purchases. Which plan you have and whether it is active. Apple handles payment, and we never see your card details.
- Usage and crashes. Which features are used, with your account ID and a device identifier, and technical crash reports. These never contain your photos or the text of your problems. You can turn analytics off in Settings.
Your first name, and a parent’s email address if you enter one, stay on your device.
Why we use it
- To store your problems and show them on your devices.
- To read, tag, and explain problems, and to write similar ones, with AI.
- To plan your reviews around your test dates.
- To provide what you paid for, and to count your monthly AI use.
- To find and fix problems, and to see which features help.
We don’t sell your data, show ads, or track you across other companies’ apps and websites.
Who handles it for us
- Cloudflare, Inc. hosts the service and stores your account, study data, and photos.
- Anthropic, PBC receives the problem text and images you send for AI features, and returns the result. Under its commercial terms it doesn’t use them to train its models.
- RevenueCat, Inc. keeps track of your subscription.
- Amplitude, Inc. receives usage events, and Functional Software, Inc. (Sentry) receives crash reports.
- Resend, Inc. sends our emails.
- Apple and Google confirm who you are when you sign in with them.
These companies are based in the United States, so your data may be stored and processed outside your country, including outside Japan and the EU. They process it only to provide their service to us.
How long we keep it
- What you add stays until you delete it. Deleting a problem deletes its photos.
- When you delete your account, we delete your account, study data, and photos within 30 days.
Your choices
- Delete your account any time in the app: My page, Settings, Delete account.
- Turn analytics off in Settings.
- Ask us what we hold about you, or ask us to correct or delete it, by writing to hello@getsanmaru.com. Depending on where you live, you may also have the right to complain to your data protection authority.
Children
Sanmaru is made for students. If you’re under 16, a parent or guardian must agree before you use the app’s photo and AI features. Parents can ask us to see or delete their child’s data at hello@getsanmaru.com.
Changes
If we change how the app uses your data, we’ll update this page and the date at the top.