Company
Practice the skill developers use every day: debugging.
Nox hands you intentionally broken code and asks you to do the everyday engineering job — understand it, find the root cause, fix it, and prove the fix with automated tests.
What is Nox?
Most coding platforms test greenfield problem solving: write a solution from scratch against a blank file. Developers rarely work that way. They enter existing codebases, understand what is wrong, fix it, and validate the result.
Nox is built around that loop: discover a challenge, read broken code, understand the failure, edit, run tests, iterate, submit for hidden-test judging, and build a profile around what you can actually debug.
Find the bug. Fix the code. Prove the fix.
How Nox works
Discover a broken build
Pick a challenge by language, category, and difficulty. Every challenge ships with real starter code — not a blank file.
Read the failure
Inspect the implementation, run the visible tests, and trace the root cause from actual output — the way on-call work feels.
Fix and iterate
Edit in Monaco, re-run tests instantly, and watch failures turn green. Reset to starter code any time without penalty.
Submit and prove it
Hidden tests judge the fix. Pass them all to earn score, XP, and rating — correctness first, always.
What we optimize for
Correctness first
A submission that does not satisfy all required hidden tests is not accepted — however high the score. Hidden tests are the source of truth.
Rating ≠ XP
Rating measures competitive debugging skill (Elo-like, from 1000). XP measures momentum — solves, streaks, daily challenges. One never substitutes for the other.
Evidence over claims
Profiles, ranks, streaks, and leaderboards only move on verified solves. No partial credit, no inflated stats.
Who Nox is for
Students & beginners
Learn debugging as a skill — not just algorithms. Read existing code, understand failures, and build confidence fixing real mistakes.
Junior developers
Get realistic reps with bugs, failing tests, APIs, and implementation mistakes before production teaches them the hard way.
Intermediate developers
Take on harder debugging: performance, security, concurrency, and production-style scenarios that stay sharp with practice.
Languages today, more tomorrow
JavaScript and Python run today; TypeScript metadata is present with execution on the way. Language execution is modular — new runtimes arrive without rewriting the platform.