For students learning design
Design principles you can apply
Your textbook defines the Liskov Substitution Principle. Can you spot a violation in real code? Interactive exercises that test application, not recall.
Get StartedS.O.L.I.D. through exercises
Each principle gets its own set of problems. Identify violations, refactor code, and verify with tests.
D.R.Y. in practice
Learn when duplication is a problem and when abstraction is worse. Real trade-offs, not textbook rules.
See the impact
Every exercise shows how a principle changes the code. You see the before and after, then build the solution yourself.
Beyond the acronym
Understand when to apply each principle and when to break the rules.
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.
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Explore our courses
Pick a course and solve your first exercise.
Dart
An interactive Dart course where you code, test, and build apps directly in your browser.
Flutter
An interactive Flutter course where you code, test, and build apps directly in your browser.
S.O.L.I.D Principles in OOP
Learn the principles of how software should be structured, so you can guide AI to build better systems.
D.R.Y. (Don't Repeat Yourself)
Learn to identify and eliminate code duplication, making your codebase cleaner and easier to maintain.
TypeScript
Learn TypeScript from variables to generics, with coding challenges you solve directly in your browser.
System Design
Learn how APIs, databases, caching, and load balancing fit together to build scalable systems.
Microcontrollers
From GPIO pins and breadboard circuits to sensors, displays, motors, and communication protocols like I2C, SPI, and UART.
Electricity and Current
Learn how electricity works, from voltage, current, and resistance to circuits, Ohm's law, and common components like resistors, LEDs, and capacitors.
Interactive courses
Every lesson is an exercise with instant feedback.