Training apprentices, I kept seeing the same thing: people watch a tutorial, nod along, and a day later can't write the code themselves. dot. is my answer to that.

There are no videos. A lesson works more like a conversation: first you predict what a piece of code will print, then you write code yourself, then a short comprehension check. You only move on when it actually sticks.

The first track is Kotlin: 12 courses and 111 lessons, from your first println to generics, coroutines, testing, Gradle and what the JVM and the compiler do under the hood. The courses build on each other, and at the end of the track there's a certificate with your name on it.

There's also an AI helper, called dot as well. You can ask it about the lesson, it gives feedback on your predictions and hands out hints. But it sticks to the course material, links its sources, and it won't give you the solution. Before you get a hint, you have to write down what you've tried and where exactly you're stuck. Surprisingly often, that alone solves it.

It's free, you don't need an account, and your progress stays on your device. Available in English and German.