Privacy Policy
Last updated: October 6, 2026
The controller of personal data processed through SQLPrep is Appvolt (앱볼트) (business registration no. 793-33-01389, 2F #201, 74 Gucheonmyeon-ro 68-gil, Gangdong-gu, Seoul 05307, Republic of Korea; [email protected]).
What we collect
- SQL you write runs in your browser. Your queries are not sent to our servers.
- Practice progress without an account is kept in your browser's local storage only.
- Account data: your email address, a hashed password and, for each problem, how many times you ran a query and when you first solved it.
- Pro waitlist: the email address and the optional interests you select.
- Site usage: for each page view we log the page path, whether you arrived from an ad or tagged link (not the click ID itself), device type, country (from our CDN), time on the page, how far you scrolled, and product events such as viewing a problem, running a query, solving it, viewing a hint or solution, signing up and joining the waitlist. We do not log IP addresses, and this log is kept on our own server; no analytics vendor receives it. Outside the EEA, the UK and Switzerland a random tab-session ID is kept in your browser's session storage until the tab closes, so page views in one visit can be grouped.
- We do not take payments. SQLPrep is free.
How we use it
To run the service, save your progress, contact waitlist members once when Pro launches, prevent abuse, improve the problems and answer support requests. We do not sell personal data.
Cookies
A session cookie (sp_session) keeps you logged in. If Google Analytics or Google Ads measurement is enabled, visitors in the EEA, the UK and Switzerland get Google's ad and analytics storage denied by default, and we do not use it for remarketing or personalized ads.
Processors
Cloudflare (network and CDN), Google (analytics and ad measurement, only if enabled) and our hosting provider.
Retention and deletion
We keep account data while your account exists. Email [email protected] to delete your account, progress or waitlist entry; we complete requests within 30 days.
Your rights
Depending on where you live (for example the EU, UK or California) you can ask to access, correct, export or delete your data, or object to processing. Contact [email protected].