Events World Cup: A Bracket Pool Built Overnight

The impact

Live and trusted before kickoff. All 25 brackets locked the morning after I started.

The draft was twelve hours away and there was nowhere good for a private group to pick. So I built the spine that evening: validated 2026 fixtures and a scoring engine, passwordless sign-in, two-step group-and-knockout picks with a hard lock at the deadline, and a league leaderboard. The next morning, twenty-five coworkers drafted their brackets and it held. No lost picks, no locked-out logins, no doubt about whether their data was safe.

From a form to a companion

A bracket pool is dull once picks lock, so the week after the draft I shipped almost daily and turned it into something people opened during matches: an in-progress score banner, a live match center with native statistics, "where to watch" links, and a verdict dot on every finished game showing whether your pick came in. A home dashboard surfaced your placement, brackets became shareable, and a stats page gave the group the bragging rights they wanted, who has the safest bracket, who took the biggest swings, who's a bracket twin.

Under it sat a fail-closed data feed, so a throttled or malformed upstream could never corrupt a result the pool had already seen. Trust was the whole reason this existed instead of a public site, so it got real engineering, not a checkbox.

The build story

The full account of the overnight build and the week of additions, and what shipping under a real deadline for a small trusted group taught me, is in the writeup: I Built a World Cup Bracket Pool in One Evening.

You can also explore a public demo running on sample players. The real pool stays private, with the real names visible only to the people who drafted that morning.

Built with Next.js, React, Supabase, Resend, and the Vercel AI SDK, deployed on Vercel.