Level up your SQL skills
Interview tasks, unlimited AI mentor and AI-generated practice for your level
Free
For learning SQL basics
All basic tasks and AI hints
No card
- 234 Easy-level tasks
- PostgreSQL, MySQL, ClickHouse, BigQuery
- Instant grading
- AI hints and explanations — 10 total
- EXPLAIN — query plan analysis
- Mock Interview mode — 1 attempt / day
- Power, streak, achievements, leaderboard
- ER schema diagrams
Premium
The trainer, without the courses
≈ $7.83/mo — save 35%
One-time payment, no auto-renewal
Visa, Mastercard, Amex via Paddle.
- Everything in Free
- +50% Power per solved task — the boost locks in forever, even after the subscription expires
- Unlimited Mock Interview attempts, up to +50% Power per clear (scales with your chosen rules)
- 1-on-1 duels: live SQL matches against real opponents, custom arenas and Power stakes
- Every hard interview problem — Medium, Hard and Expert (Google, Meta, Tesla…)
- Unlimited AI hints and error explanations
- AI-generated tasks for your level — up to 10 / day
- Community top solutions
- Timed certification exam — a verifiable certificate for every level
Pro
The trainer and all the courses
≈ $9.83/mo — save 34%
One-time payment, no auto-renewal
Visa, Mastercard, Amex via Paddle.
- Everything in Premium
- SQL Course — 12 modules, 77 lessons: from the first SELECT to window functions, a capstone project and a path to the certificate
- Data Analysis Course — 13 chapters, 83 lessons: Python and pandas in the browser, product metrics, cohorts, A/B tests and eleven investigations
- SQL Performance course — 10 chapters, 49 lessons: EXPLAIN ANALYZE, the four scan types, indexes and sargability, JOIN algorithms, work_mem and planner statistics
- BigQuery course — 8 chapters, 27 lessons: arrays and STRUCTs, windows with QUALIFY, shards and wildcard tables, and the bill for bytes read
- Data Engineering course — 10 chapters, 58 lessons: intake and high-water marks, a star-schema warehouse with SCD2, Airflow 3 DAGs, ClickHouse and MergeTree, backfills, data-quality checks and Kafka
- ClickHouse course — 8 chapters, 41 lessons: aggregate combinators, arrays as columns, funnels and retention, time without gaps, joins, and the layout that sets the price of an answer
- Kafka course — 10 chapters, 59 lessons: the log and retention, writes without loss and reads without duplicates, rebalances and consumer lag, the message contract, exactly-once and stream processing
Pro includes everything in Premium and adds every course on the platform
What the subscription gives you
+50% Power per solve
Boost locks in forever — stays after subscription ends
Courses, not just the trainer
Courses on SQL, Data Analysis, SQL Performance, BigQuery, ClickHouse, Data Engineering and Kafka — Python, pandas and statistics right in the browser. All of them open in full on the Pro plan.
Unlimited Mock Interview
Removes the “1 attempt per day” cap, plus up to +50% bonus Power per clean pass
Hard interview problems
Medium, Hard and Expert from Google, Meta, Tesla and others — the easy ones are free too
Unlimited AI mentor
Hints and error explanations with no limit
AI-generated tasks
Up to 10 unique tasks per day for your level
1-on-1 duels
Live SQL matches against real opponents, custom arenas and Power stakes
Certification exam
A timed exam and a verifiable certificate for every level
Top community solutions
Learn from the best — see how others solve