For CS students

Stop memorizing. Start solving.

Reading about linked lists is easy. Implementing one under test pressure is where learning happens. Solve exercises that build real understanding.

Every exercise asks you to write code. Fill in the blank, complete the function, fix the bug.

Submit your answer and see results in milliseconds. No setup, no IDE, no waiting.

Every lesson explains the principle before you apply it. You learn when to use each structure and why.

Built for active learning

The way your CS professor wishes you studied.

Write code from lesson one

Every lesson is an exercise you solve in your browser. Real code, real tests, real feedback.

Write a greeting function

main.ts

function greet(name: string) {

return `Hello, ${name}!`

}

Each concept builds on the last. You always know what to learn next.

Quizzes, fill-in-the-blank, matching, and code keep every lesson engaging.

Submit your answer and see test results in milliseconds.

Learn by doing

Solve exercises in your browser from the first lesson.

Pick a course and solve your first exercise.

An interactive Dart course where you code, test, and build apps directly in your browser.

An interactive Flutter course where you code, test, and build apps directly in your browser.

Learn the principles of how software should be structured, so you can guide AI to build better systems.

Learn to identify and eliminate code duplication, making your codebase cleaner and easier to maintain.

Learn how APIs, databases, caching, and load balancing fit together to build scalable systems.

Interactive courses

Every lesson is an exercise with instant feedback.

Solve your first exercise in under a minute.