Privacy Policy
Last updated September 21, 2026. See also the Terms of Service.
This Privacy Policy explains what information https://sysdesignprep.com (the "Site") collects, how it is used, and the choices you have. We keep it short because we collect little.
1. What we collect
Without an account. The Site works without signing in. Study and practice progress (time spent per question and mode, revealed answers) is stored in your browser's local storage and never leaves your device unless you sign in.
With an account. When you sign in with Google we receive your name, email address and profile picture from Google, and we create a profile record. We do not receive your Google password. Once signed in, your study session records (question, mode, start and end time, active seconds) are synced to our database so they follow you across devices.
When you buy Pro. Checkout is handled by Stripe. Stripe collects your payment details, billing address and, if you provide one, tax id. We receive your Stripe customer id, the plan you bought, its status and renewal date, and the billing country needed for tax. We never see or store full card numbers.
Automatically. Like most sites we receive standard server logs (IP address, browser, pages requested, timestamps) from our hosting provider, and we use Google Analytics to understand which pages are used. Analytics data is aggregated and does not identify you to us.
2. How we use it
- to run the Site and keep you signed in;
- to sync your progress across devices;
- to process payments, manage subscriptions, prevent fraud and comply with tax law;
- to answer your support requests;
- to understand aggregate usage and improve the content.
We do not sell personal information and we do not use it for third-party advertising.
3. Legal bases (EEA and UK)
We process account and payment data to perform our contract with you; server logs, fraud prevention and analytics under our legitimate interest in running a secure and useful site; and anything else with your consent, which you can withdraw at any time.
4. Who we share it with
Only the services that make the Site work, each bound by its own privacy terms:
| Provider | Purpose | Data |
|---|---|---|
| Supabase | authentication and database hosting | profile, session records, subscription status |
| Stripe | payments, invoices, tax, billing portal | payment and billing details |
| Vercel | hosting and server functions | request logs |
| sign-in; analytics | Google account basics; aggregated usage |
We may also disclose information if the law requires it or to protect the rights and safety of users or the Site.
5. Cookies and local storage
We use local storage for your theme preference and, when signed out, your study progress. Supabase sets a cookie or local storage entry to keep you signed in. Google Analytics sets its own cookies; you can block them with a browser extension or by disabling cookies for this site without losing any functionality other than being signed in. We do not use advertising cookies.
6. Retention
Account data is kept while your account exists. Session records are kept so your history stays available. Payment records are kept for as long as tax and accounting law require (typically 7 years). Server logs are kept for a short period by our hosting provider. If you delete your account we delete your profile and session records within 30 days; Stripe records are retained as required by law.
7. Your rights
Depending on where you live you may have the right to access, correct, export or delete your personal information, to object to or restrict its processing, and to complain to a data protection authority. To exercise any of these, email us. We will respond within 30 days. Deleting your account can also be requested by email at any time.
8. Security
Data is transmitted over HTTPS and stored with providers that maintain industry-standard security programs. Access to production data is limited to what is needed to operate the Site. No system is perfectly secure; if we learn of a breach affecting your data we will notify you as the law requires.
9. International transfers
Our providers operate in the United States and other countries. Where required, transfers from the EEA or UK rely on standard contractual clauses or an adequacy decision.
10. Children
The Site is not directed at children under 16 and we do not knowingly collect their personal information. If you believe a child has provided us data, contact us and we will delete it.
11. Changes
We may update this policy. The date at the top shows the latest version. Material changes will be announced on the Site.
12. Contact
Privacy questions or requests: support@sysdesignprep.com.