Adaptive difficulty from progress
The next difficulty can move with recent results and skill level. Rating is reported separately and does not choose difficulty.
From symptom to measurable practice
A compact lab for debugging decisions
Practice stays focused on evidence while ten skills, a rating, weekly solved counts, streaks and achievements make progress visible.
From code to learning
Choose your first language
Nine verified programming languages. The interface and feedback support five languages, while editorial documentation initially publishes in English and Brazilian Portuguese.
- 1Choose a language
- 2Investigate the bug
- 3Check the solution
- 4Read explainable feedback
- 5Track your progress
PythonPractice now →JavaScriptPractice now →TypeScriptPractice now →JavaPractice now →C#Practice now →SQLPractice now →KotlinPractice now →SwiftPractice now →C++Practice now →Interface and feedback: English, Português, Español, العربية, 한국어. Published docs: EN / PT-BR.
The mark of a held standard
Does the reasoning hold? Prove it.
Every challenge ends the same way: your reasoning either holds under the verdict or it does not. The shield carries that idea — a structure under load, tested until it proves itself.
Move your pointer across the shield
Ten skills with their own levels
Each solved challenge awards 60, 100, 140, 180 or 220 XP per inferred skill. Skills follow their own level 1–5 curve.
Rating and weekly ranking
A rating inspired by Elo reflects solved results, challenge difficulty and time. The weekly board counts solved challenges.
Streaks and achievements
A solved challenge on a UTC calendar day keeps the streak moving. Reachable milestones recognize consistency and skill progress.