Be sure of the number before you say it.
What is Atterna
Atterna is a hands-on learning platform for data analysis in the AI era: you practise on a fictional marketplace dataset how to ask a precise data question, check whether a number (your own, a colleague’s or an AI’s) is right, and defend the decision it leads to.
The level check suggests SQL from zero, cases or the full simulator.
Find your level →Why it matters
Numbers reach you already made: from a dashboard, a colleague or an AI assistant. Most look right. Some count the wrong people, divide by the wrong total or double rows when tables are joined. Atterna trains the habit of checking on the data what a number counts before you repeat it, and of defending it once you have.
The method: Ask → Check → Review → Decide
- Ask: turn a vague request into a definition — who, what, over which period.
- Check: reproduce the number, compare it with a known total, look for duplicated rows and wrong denominators.
- Review: get feedback and look for the plausible mistake before someone else does.
- Decide: recommend an action and say what would change your mind.
One path, two levels, one marketplace
- Wrong NumberFree, 3 minutes, no accountAnyone, no SQL needed
A browser game: three colleagues each ask for a customer count, and one database of 7,136 accounts gives three different right answers (2,141, 3,670 and 2,339). You learn that a number is only right for a stated question.
Open Wrong Number → - Level checkFree, 3 minutes, no accountAnyone deciding where to start
Six questions — reading a table, filters, GROUP BY, COUNT DISTINCT, row multiplication in JOIN and one analyst-judgement question — suggest a starting point.
Open Level check → - Atterna StartFree: days 1–2 without an account, all 10 days with a free accountComplete beginners: SQL from zero
A 10-day SQL course on marketplace data: tables and a first query built with the mouse, then filters, CASE, GROUP BY and HAVING, WITH, LEFT JOIN, join traps and window functions. SQL runs in the browser and every answer is checked automatically.
Open Atterna Start → - Atterna CasesCase 1 free without an account; cases 2–3 are the case rounds in Atterna Foundations (€19) and are included in Atterna Analyst (€59)People who know basic SQL
Short work stories that train analyst judgement: clarify the request, define the metric, write SQL and defend the call. The first case, Bigger baskets?, asks whether a promo code really grows order value.
Open Atterna Cases → - MeridianEpisode 1 free with a free account; episodes 1–8 are Atterna Analyst (€59 one-time, early-access price)People who already answer work questions with data
An analyst simulator on a fictional European marketplace. Stakeholders ask, you query, every SQL answer is checked on a second dataset too, and each episode ends in a decision backed by your numbers (episode 1 also in a written memo). Eight episodes, each opening when the previous one is done: a record week after a promo, a broken A/B split, cohorts and retention, seller metrics, delivery unit economics, a sales forecast, a seller-side experiment and a 15% drop in weekly GMV.
Open Meridian →
Who it is for
- People who want to learn data analysis or SQL from zero
- Junior analysts and course graduates who want practice on realistic business tasks
- Product managers, marketers and founders who get numbers from dashboards or AI assistants and need to judge them
Status
Atterna is in early access (autumn 2026). SQL is free: all 10 days of Start with a free account. You pay only for practice: case rounds (€19) and Meridian (€59). Without an account: Start days 1–2, case 1, the Wrong Number game, the level check, the guides and tools. Two paid levels at one-time early-access prices: Atterna Foundations, €19 (case rounds: cases 2–3), and Atterna Analyst, €59 (Meridian episodes 1–8 and everything in Foundations). Within 24 hours of your request, Kirill emails a payment link. Access opens within 24 hours of confirmed payment.
Who writes the guides
Kirill Sk is a Data Product Manager based in the Netherlands and the founder of Atterna. He has led analytics teams and writes about checking numbers, defining metrics and working with data alongside AI.
Questions
Is Atterna free?
SQL is free: all 10 days of Start with a free account. You pay only for practice: case rounds (€19) and Meridian (€59). Without an account you can play Wrong Number, take the level check, read the guides and do Start days 1–2 and case 1. The paid levels are one-time early-access prices, not a subscription.
Do I need to know SQL?
No. Wrong Number needs no code, and Start teaches SQL from zero for free. The judgement Atterna trains — who was counted, what a share is of, which period — carries over to spreadsheets, Python or R. If you already write SQL, the level check suggests where to begin.
Is Atterna a prompt-engineering course?
No. Prompting is about wording; Atterna trains the judgement behind it: which definition a number needs, what to check, and when a result is not ready to use. That works the same with a colleague, a dashboard or an AI assistant.
Does Atterna use AI to grade my work?
Lesson checks are deterministic, and SQL tasks are also run on a second dataset to catch queries that only work by accident. Separately, the free AI Answer Checker offers optional AI feedback with your permission. That feedback suggests checks; it cannot verify data it has not seen and does not grade your lessons.
In which languages is Atterna available?
The core learning products are available in English and Russian. English is the default. All guides are available in English; translated guides also have a Russian version.
Who makes Atterna?
Atterna is founded by Kirill Sk, a Data Product Manager based in the Netherlands who has led analytics teams. The data and characters in the practice marketplace are fictional.