Practice real data-interview questions against a live database in your browser. Write SQL, hit check, get graded instantly. No setup, no signup.
Not multiple choice. You write the query, it runs against real data, and you find out immediately whether it's right.
A full SQLite engine runs in your browser. Your query executes against real rows and is graded against the correct result set — not a keyword match.
Joins, aggregation, subqueries, CTEs, window functions, and date logic across three realistic schemas: e-commerce, SaaS, and HR.
Miss one? It comes back at the right interval, so the patterns stick before your interview — not after.
Stuck? Reveal hints one at a time, then read a worked solution with an explanation of the approach and the gotchas.
Nothing is uploaded. Your queries and progress stay in your browser. No account required to start.
See what you've solved, what's left, and what's due for review. Build a streak toward interview day.
Problems span easy warm-ups to hard window-function questions.
15 problems are free forever. Unlock the full set, every solution, and spaced review.
They're original problems written to mirror the patterns that data-analyst and data-engineer interviews test — joins, aggregation, window functions, and more. They are not copied from any company's question bank.
SQLite, running in your browser via WebAssembly. The core concepts transfer directly to PostgreSQL, MySQL, Snowflake, and BigQuery.
No. You can start immediately. Your progress is saved in your browser's local storage. Pro is unlocked with a license key sent to your email after purchase.
No. The database and grading run entirely client-side. Nothing you type is uploaded anywhere.