Legal
Privacy Policy
Effective date: July 17, 2026
Overview
MasterTheBook AI (masterthebook.com) is a subscription study-coach service. This Privacy Policy describes what information we collect, how we use it, and the choices you have. We do not sell your personal information. The service is primarily US-operated; privacy requests may be sent to legal@masterthebook.com.
Information we collect
Account data: email address and authentication identifiers when you sign up or sign in (including passwordless links, Google, or Apple). Learning data: mastery scores, notes, journal entries, study goals, study progress, spaced-review history, and coaching interactions needed to run the product. Usage data: feature usage, coaching call counts, and first-party product analytics events stored in our database (not a third-party analytics SaaS). Payment data: billing status and Stripe customer identifiers — we do not store full credit-card numbers. Optional profile data: survey or demographic fields you choose to provide.
How we use information
We use your information to operate and improve MasterTheBook, personalize coaching and review schedules, enforce plan limits, process payments, respond to support requests, detect abuse, and understand product usage in aggregate. We may use anonymized or aggregated data for research and product improvement.
AI processing
When you use AI coaching, your prompts and relevant book and learner context are sent to our servers via /api/coach and forwarded to Anthropic for processing. API keys never appear in your browser. We configure our AI provider not to use your content to train their public models where the provider offers that control; see the provider's terms for how they process API data. Our operational coach request logs record metadata (such as outcome, model, token counts, and book id) and intentionally omit full prompt bodies. Derived learning signals (such as mastery state and weak areas) may be stored to provide continuity across sessions.
Third-party processors
We rely on service providers that process data on our behalf: Supabase (authentication, database hosting, and first-party analytics event storage), Stripe (payments and subscription management), Anthropic (AI coaching), Vercel (application hosting and infrastructure logs), Resend (transactional email), Sentry (error reporting), and Upstash (distributed rate limiting). Product analytics events are stored in our Supabase database rather than a separate analytics vendor. Each provider handles data according to their own terms and our agreements with them.
Your choices
You can disable AI coaching in your preferences. Optional cohort or research features require your explicit consent and are off by default. Where a research study publishes anonymized results, participation is opt-in from account settings, your data is identified in the published dataset by a random participant code rather than by your account, and you can withdraw at any time — though once an anonymized dataset has been published, individual rows can no longer be traced back and removed. You can dismiss incorrect learner-model inferences from your account. You can cancel your subscription and delete your account from account settings.
Data retention and deletion
We retain account and learning data while your account is active. When you delete your account, we remove user-owned records and your authentication identity. Some anonymized records (such as aggregated analytics or support history with your identity removed) may be retained for fraud prevention, billing disputes, and legal compliance. If you delete your account while a subscription is active, cancel the subscription first in the billing portal to avoid unexpected charges.
Security
We use reasonable technical and organizational measures to protect your data, including encrypted transport and access controls on our infrastructure. No method of transmission or storage is completely secure, and we cannot guarantee absolute security.
Children
MasterTheBook is not directed at children under 13, and we do not knowingly collect personal information from them. If you believe a child has provided us data, contact legal@masterthebook.com and we will delete it.
Changes and contact
We may update this policy from time to time. Material changes will be reflected by an updated effective date on this page. Questions or requests regarding your data: legal@masterthebook.com.