Rootin4

Every World Cup product tries to predict who lifts the trophy. Rootin4 answers a smaller, more personal question: who actually plays at the seat you already bought?

The riddle

The 2026 World Cup spans three countries, sixteen stadiums and 104 matches — and tickets are sold by match number, months before the bracket exists. If you hold a knockout ticket, your seat reads like a puzzle: Winner Group K versus a third-place finisher from Group D, E, I, J or L. Rootin4 translates that into probabilities per team and per pairing, and into one plain-language answer: should you get on the plane?

How the numbers are made

A Monte Carlo engine replays the entire tournament thousands of times per question — all 104 fixtures, FIFA tiebreakers, the third-place allocation, penalty shootouts — from Elo-based team strengths. The probability next to a team is simply the share of simulated tournaments in which it reaches your match.

Once the tournament kicks off, reality takes over: every recorded result is locked into the simulations, and both teams' ratings are updated from it before the remaining fixtures are sampled. The small chart beside each probability is that number's history — one step per real event, the way a market re-prices on news.

The agent that audits itself

On top of the engine sits an agent built with Google's Agent Development Kit and Gemini 2.5. Every model call and tool call is traced to Arize Phoenix — and the agent can read those traces back. Ask it to audit its calibration: when the evidence shows a systematic bias, it corrects its own priors and says so. The system is designed to sharpen as the tournament progresses — exactly when your decision gets urgent.

Why you can trust it

Three rules keep us honest. Every number is computed live by the engine — no placeholders, ever. Every change of mind is public — results, corrections and re-pricing all land in the activity feed and on the charts. And if the backend is unreachable, we show nothing rather than something made up.

We can't tell you who lifts the trophy in New Jersey on July 19. We aim to tell you, with calibrated honesty, who is most likely to be standing on the pitch in front of your seat.

Make the call.

Rootin4 is an independent forecast built for the Google Cloud Rapid Agent Hackathon (Arize track). Not affiliated with FIFA. Not betting advice. Source on GitHub.