Whoever ships
first wins.
Real-time 1v1 coding battles. Get matched by ELO, solve under a 15-minute clock, climb the global ladder.
Three steps to dominance.
Get paired with a developer at your exact ELO. The system matches you in seconds — no lobby, no waiting.
Race on the same problem under a shared 15-minute clock. Write clean code — not just fast code.
First correct submission wins the ELO delta. Ties go to the AI tiebreaker judging on complexity and code quality.
Where do you stand?
A fair fight, every time.
CodeDuel uses chess-style ELO ratings. Win against a higher-rated opponent and you gain more. Lose to a lower-rated one and you lose more. The system self-balances — your rank reflects reality.
| Players | Problem | Difficulty | Result |
|---|---|---|---|
ND CN | Two Sum Optimization | easy | Win +15 ELO |
NP BN | LRU Cache Implementation | hard | Loss −12 ELO |
RK AD | Word Search II | hard | Win +24 ELO |
AK SX | Trapping Rain Water | medium | Win +18 ELO |
PU BH | Course Schedule | medium | Win +21 ELO |
First to submit isn't always the winner.
When two players submit within the same window, a deterministic layer measures real runtime and complexity — then an AI narrates exactly why one solution won.
- Runtime and memory measured from actual execution, not self-reported
- Complexity class inferred from benchmark curves — O(n) vs O(n²)
- AI explains the verdict in plain English, can't override the score
Built by developers, for developers.
CodeDuel is open source and entirely community driven. Have a feature request, found a bug, or want to contribute new algorithmic challenges?
Ready to compete?
Prove your worth in real time.
Join 50,000+ developers. Your first match is one click away.
Settle the debate.
Add your coworkers, classmates, or rivals. Challenge them to private duels to definitively prove who the better developer is. Track your head-to-head records and climb your private leaderboards.