Crux

Privacy Policy · Last updated May 2026

Introduction

Crux is an exam preparation mobile application provided by SMGC Technologies (“we”, “us”). This Privacy Policy explains how we collect, use, store, and protect your information when you use the Crux app and related services.

Information we collect

We may collect the following categories of information:

• Account details: email address, display name, and authentication identifiers.
• Sign-in: when you use Google or Apple, we receive tokens and profile information as permitted by those providers.
• Study activity: topics you read, revision and spaced-repetition history, confidence signals, and related learning analytics needed to run the product.
• Preferences: study windows, revision windows, notification preferences, and exam preferences (including primary and secondary exams).
• Technical data: information required to operate the service securely (e.g. device tokens for push notifications where enabled).

How we use your information

We use your information to:

• Provide and personalise your experience, including daily topic curation tailored to your goals.
• Power the spaced repetition engine and track your progress across layers (Read, Understand, Remember, Why).
• Send study window and revision reminders when you enable notifications.
• Send transactional emails (for example, password reset) when you request them.
• Maintain security, troubleshoot issues, and improve the app.

Data storage

Your data is stored in industry-standard cloud infrastructure. Application data is held in a PostgreSQL database hosted on Supabase; short-lived cache data may be stored in Upstash Redis. Our backend runs on Railway. We use reasonable administrative, technical, and organisational measures designed to protect your information.

Third-party services

Crux relies on third-party processors, including:

• Google Sign-In and Apple Sign-In for authentication.
• Razorpay for payment processing.
• Firebase for push notifications.
• Resend for transactional email delivery.
• Anthropic Claude API for certain content-generation features.

These providers process data under their own terms and privacy policies. We share only what is needed to provide the service you request.

Data retention

We retain your information while your account is active and as needed to provide the service. If you ask us to delete your account, we will delete or anonymise your personal data in line with our processes and applicable law, subject to limited exceptions (for example, legal or security requirements).

Children’s privacy

Crux is not directed at children under 13, and we do not knowingly collect personal information from children under 13. If you believe we have collected such information, please contact us and we will take appropriate steps.

Your rights

Depending on where you live, you may have rights to access, correct, or delete your personal data, or to object to or restrict certain processing. To exercise these rights or ask questions about your data, please contact us using the details below.