Designed, built, and run solo: a live community ranking product for roller coaster riders. Riders drag-sort the coasters they have ridden, and the board turns those rankings into a community ranking. Built in React and TypeScript on Supabase, with a Bradley-Terry ranking pipeline running in Postgres that recomputes every five minutes, and edge caching on Cloudflare for fast public reads. Grown on a zero budget with community outreach, SEO, and a submission/referral flow; over 100 community submissions so far. Open source (MIT code, CC BY data).