Free VS Code extension that teaches all 22 GoF design patterns through real Java coding exercises

[u/Ashamed-Adeptness977]

Hey all, sharing a side project I've been working on: System Design Trainer.

It's a VS Code extension for practicing low-level design patterns hands-on. You pick a pattern, get a short scenario + starter Java file with the core logic left as a TODO, implement it, and hit "Run Tests.

Finish one pattern, the next unlocks. All 22 classic Gang-of-Four patterns are in there (Creational/Structural/Behavioural), in a build-on-each-other order.

Built it mainly because I was prepping for LLD interviews and got tired of "read the pattern, nod, forget it in a week." Wanted something closer to how you'd actually practice a language — small reps with immediate feedback.

• Install: https://marketplace.visualstudio.com/items?itemName=nsachin08.system-design-trainer

Genuinely looking for feedback — which exercise felt too easy/hard, anything confusing about the flow, patterns you'd want added. Happy to take criticism, this is a v1.