System design interviews
Design systems. Pass interviews.
Interactive exercises that make you design real systems. Practice trade-offs, scaling decisions, and architecture patterns before the whiteboard.
Start the System Design CourseReal architecture problems
Design URL shorteners, chat systems, and notification pipelines. Each exercise mirrors what interviewers actually ask.
Trade-offs, tested
Every design decision has trade-offs. The exercises test whether you understand them, not whether you memorized a diagram.
Instant feedback on your reasoning
Know immediately whether your design holds up. Structured feedback on each decision, not a vague "looks good."
System Design + SOLID + DRY
Architecture thinking for interviews and production.
Write code from lesson one
Every lesson is an exercise you solve in your browser. Real code, real tests, real feedback.
Structured progression
Each concept builds on the last. You always know what to learn next.
Multiple exercise types
Quizzes, fill-in-the-blank, matching, and code keep every lesson engaging.
Instant feedback
Submit your answer and see test results in milliseconds.
Learn by doing
Solve exercises in your browser from the first lesson.
Join over 5,000 learners
Explore our courses
Pick a course and solve your first exercise.
Dart Course
An interactive Dart course where you code, test, and build apps directly in your browser.
Flutter Course
An interactive Flutter course where you code, test, and build apps directly in your browser.
S.O.L.I.D. Course
Learn the principles of how software should be structured, so you can guide AI to build better systems.
D.R.Y. Course
Learn to identify and eliminate code duplication, making your codebase cleaner and easier to maintain.
System Design Course
Learn how APIs, databases, caching, and load balancing fit together to build scalable systems.
Interactive courses
Every lesson is an exercise with instant feedback.
Stop memorizing diagrams. Start designing.
Interactive system design exercises with instant feedback.
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