FAQ
Frequently asked questions
Do I need an account?
No. Your first exercise works without one, and your draft is kept in this browser. Create an account to sync progress across devices.
Which SQL dialect do you use?
DuckDB SQL (version 1.5.1). Concepts carry over to other databases; exercises point out dialect-specific functions.
Which Python and pandas versions?
Python 3.14 with pandas 3.0.2. The version is shown in the workspace.
How is my answer graded?
The server re-runs your solution on the published dataset and on new hidden variations, then compares the full typed result, including duplicates and quarantined rows.
Is my code run safely?
Graded code runs in an isolated virtual machine with no network access and no access to other learners or to our systems.
Are the datasets real?
No. Datasets are original and fictional, written to look like real workplace exports.
What's free and what's Pro?
15 starter exercises (each in visual, SQL and Python), the daily challenge, every lesson and the glossary are free. Pro and Lifetime plans open every exercise in all three tracks; Pro also includes the AI tutor.
Can I cancel or get a refund?
Cancel any time from Billing and keep access until the end of the paid period. Your first purchase can be refunded in full within 14 days.
What happens to my data?
We keep your account and progress, not the code you submit. You can delete your account at any time. See the privacy policy for details.