Learn how AI works by defending one. You write the system prompt that guards a rule, then real attacks try to break it. Beat the playground, then build real projects. No signup to start.
We hand you a live model and a room full of people trying to hijack it: jailbreaks, prompt-injection, off-topic bait. Your only defense is the system prompt you write. Run the attacks, tighten your wording, and run them again until nothing holds. It turns prompt-writing into a real game of building the toughest instructions you can.
From your first line of Python to shipping with AI and prepping for the AP exam. Pick a lane, or wander across all of them.
From tokens and embeddings to RAG, agents, and shipping an AI-powered app.
Python · 300+ lessonsAll five Big Ideas, with Create Task practice mapped to the real rubric.
Python · 48 lessonsAll ten units of object-oriented Java, from primitives to recursion, autograded.
Java · 80 lessonsUSACO and Codeforces-style problems judged on a real C++ compiler.
C++ · 18 problemsMost sites that teach coding hand you videos to watch and quizzes to forget. Here you write code and run it, starting in the first lesson.
The quickest way in is the playground. You write the system prompt guarding an AI, then real attacks try to break it, and within a minute you know whether your defence held. Reading about prompt injection is nothing like watching your own rule get talked around.
Behind that sits the curriculum: AI engineering, both AP Computer Science courses, and contest problems judged on a real compiler. Every reference solution runs against its own tests before it ships, so nothing is graded against an answer key nobody checked.
Free, runs in your browser, no signup to begin. Open a lesson and run your first line.
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