Vol. I · Interview Practice · 2026
Read the problem.
Write the answer. Run it.
A small, open studio of coding and system-design problems. Python and JavaScript, graded entirely in your browser. No accounts, no telemetry, no servers between you and the work.
In this volume
On the press
Code runs in Pyodide (real CPython 3.12 on WebAssembly) and a sandboxed JavaScript Worker. Each problem is a folder in the repo — contributing a new one is the same as opening a pull request with a Markdown file and a tests.json.
The grader is declarative: every problem declares a signature and a validator (exact, set, set_of_sets, ...). The harness handles the rest, so problem authors never ship executable code.
Open the problem setMIT licensed · Pyodide 0.27 · Next.js 16