The build that actually wins the matchup.
Pick your champion and the enemies they're up against. The optimizer scores every item by its Wilson lower-bound win rate against the picked comp — not raw popularity — and surfaces the swaps the data says beat the meta default.
Pick a champion to build.
Choose your champion and role on the left, then optionally fill the enemy team — the optimizer reads per-matchup item win rates and surfaces the swaps that beat the meta default.
About the Build Optimizer
The Build Optimizer is YordleDiff's free League of Legends build tool. Pick your champion and role, then optionally pick the enemy team — and the optimizer returns the starting item, the popular meta path, the highest-win-rate path, and a comp-aware path that the data says wins against the exact enemies you've picked. Situational picks are grouped by category — anti-heal, anti-tank, defensive, and damage — so you can read the build at a glance. For a full draft view including bans, jungle path, and team-wide build coordination, use the Team Builder.
How does the Build Optimizer work?
methodologyFor each item slot, the optimizer scores every candidate item using the Wilson lower bound on its win rate against the picked enemies — not raw win rate. That keeps the recommendation honest when a slot has small samples and avoids high-variance flukes. If the Wilson-best comp pick beats the meta-default at the same slot, it's swapped in and labelled with the enemy it counters. Boots and starting items use the same Wilson scoring; boots position adapts to the matchup instead of being fixed.
What rank do the build stats come from?
data sourceRanked Emerald+ games on the current patch (16.11). Per-matchup item win rates are scraped per role and per opponent, so the build for Riven into Darius is calibrated against the actual Riven-vs-Darius sample rather than the global Riven average.
Is YordleDiff free?
pricingYes. The Build Optimizer and every other tool on the site are currently free to use, with no login or signup needed. Everything is computed in your browser — nothing you enter is uploaded.
Why does my build sometimes differ from the most popular path?
comp-aware divergenceBecause the popular path is what the average player builds, not what wins. When the data shows a different item wins more against the specific enemies you've picked, the optimizer surfaces that — with a confidence indicator so you can tell when the comp-pick has a strong sample behind it and when it's a tighter call.