Elo Rating API

Compute Elo ratings — the rating system behind chess, esports, games and competitive leaderboards. The expected endpoint takes two players' ratings and returns each side's win probability using the classic logistic formula 1 / (1 + 10^((Rb − Ra) / 400)), names the favourite and reports the rating gap. The match endpoint applies a result — a win, loss or draw for player A — and returns both players' updated ratings, the exact points each one gained or lost, and the expected scores, using a configurable K-factor (32 by default; lower for established players, higher for newcomers, so ratings settle or move quickly as you choose). An upset is rewarded with a bigger swing and a draw shifts points toward the underdog, exactly as Elo intends. Everything is computed locally and deterministically, so it is instant and private — no players or leaderboard are stored. Ideal for games and esports matchmaking, chess and board-game apps, tournament and ladder systems, ranking and reputation features, and A/B-style skill comparisons. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This computes ratings from inputs you provide; it does not store a leaderboard or look up a player's rating.