Free · open · one structured queue
Prepare for the whole interview, not just the coding round.
Coding, SQL, machine learning, math, agents/LLMs, and system design — organized by pattern, with a practice editor, a tickable study plan, and links to the original problems. Everything runs in your browser; your progress stays on your device.
Tracks
Coding
Data-structures & algorithms, grouped by pattern.
272 problems
SQL & Databases
Query patterns, window functions, engine internals.
3 lessons
Machine Learning
Features, models, training, metrics, debugging.
9 lessons
ML System Design
Framework + real ML system walk-throughs.
11 lessons
Agents & LLMs
LLM internals, agent design, tools, RAG, evals.
18 lessons
GenAI System Design
Designs from smart-compose to text-to-video.
10 lessons
System Design
Classic distributed-systems design.
29 lessons
Object-Oriented Design
OOD problems and modelling.
14 lessons
Math
Probability, statistics & inference, linear algebra.
3 lessons
Case Studies
Worked, end-to-end case studies.
9 lessons
How it works
Practice like the real thing
Every problem has a built-in editor with syntax highlighting. It doesn't run by default, on purpose, to mimic an interview screen. Reveal the reference solution when you're ready.
Follow one queue
The study plan interleaves a coding rep and a reading session each day. Tick items off; your place is saved in your browser.
Learn the patterns
Problems are grouped by the pattern they teach, and each links to the original on its source site.