Practices
Real production problems, not toy puzzles.
Curated, production-grade practice problems with reference solutions. Each track is built from a public source repository, so new questions appear here within minutes of being added there. Filterable by category, difficulty, and a curated must-have set for senior interviews.
Pick a practice track
Each problem hides its solution by default. Try it first; the solution unlocks with one click and stays unlocked for your next visit.
System Design Live
Interview-style design questions: URL shorteners, news feeds, chat, ride sharing, video streaming. Capacity math, partial diagrams you complete, follow-up scenarios with answers.
Data Engineering Live
Real production scenarios: late Kafka events, schema drift, silent ETL bugs, SQL plan reading, cost incidents. Inspired by what actually breaks in production.
AI Engineering Roadmap & Concepts
No practice problems yet on this track. The roadmap and concept library cover the patterns; production problems are on the way.
How to use a practice track
A practice track is a tool, not a checklist. Three habits make it useful.
Solve before you peek
Solutions are gated for a reason. Spend 15 to 30 minutes on a problem before opening the answer, even when the answer feels obvious. The struggle is where the learning happens.
Start with must-haves
Each track has a curated "interview must-have" filter. Those are the problems that show up in almost every senior loop. Solve those first; the rest are depth and variety.
Revisit at intervals
Solving once is not learning. Try a problem in week 1, again in week 4, again in week 12. The spaced repetition turns "I solved it once" into "I can explain it in an interview."
Looking for the path? The roadmaps put the practice in order. The concept libraries explain the underlying ideas.