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, per-track progress, 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.
0 / 272 problems
SQL & Databases
Query patterns, window functions, engine internals.
0 / 36 problems
Machine Learning
Features, models, training, metrics, debugging.
0 / 9 lessons
ML System Design
Framework + real ML system walk-throughs.
0 / 11 lessons
Agents & LLMs
LLM internals, agent design, tools, RAG, evals.
0 / 18 lessons
GenAI System Design
Designs from smart-compose to text-to-video.
0 / 10 lessons
System Design
Classic distributed-systems design.
0 / 29 lessons
Object-Oriented Design
OOD problems and modelling.
0 / 14 lessons
Math
Probability, statistics & inference, linear algebra.
0 / 3 lessons
Case Studies
Worked, end-to-end case studies.
0 / 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 the pattern map
Coding and SQL are laid out as directed pattern graphs: finish a topic and the nodes that build on it unlock. Each node fills in and turns green as you solve its problems.
Your progress, your device
Tick problems and lessons as you go. Every track shows a live completion percentage, saved in your browser — no account, no tracking.