Fantasy Football Analyzer

Free, open-source league analysis and a live draft assistant for Sleeper, ESPN, and Yahoo fantasy football leagues. No accounts, no ads, no server-side storage: credentials stay in the browser and pass straight through to the platform APIs.

Live: https://fantasyfootballanalyzer.app/

What it does

Draft tools (upcoming season)

• Draft Room: log a live snake or auction draft (or run a mock against AI opponents) with rankings, tiers, auction values scaled to your league, live inflation, stack/handcuff detection, nomination advice, comfort-bid math, positional-run and tier-break alerts, and an end-of-draft recap with instant grades
• Live Sync pulls picks straight from a running Sleeper draft
• Rankings: FantasyPros, ESPN, and Sleeper side by side, refreshed daily by a GitHub Action, with a target/avoid list that follows you into the draft, plus per-position views (/rankings/qb .. /rankings/flex)

The Rankings board and the Draft Room work with no login at all (guest mode). A loaded league is only needed for the league-analysis tools below.

League analysis (any loaded season)

• Draft grades from actual season production, with a per-team leaderboard and points-left-on-board
• Trade verdicts and waiver receipts in points-above-replacement
• Luck analysis: expected wins, all-play records, PF-rank vs W-rank
• Team hub pages, head-to-head grids, manager skill scores
• League history with a champions wall, season records, a week-by-week season story, and auto-generated awards (PNG-exportable for the chat)

Development

npm install
npm run dev          # local dev server
npm run test:run     # vitest suite
npm run build        # typecheck + production build
npm run deploy       # publish dist/ to gh-pages

Draft data lives in src/data/draftPool.<season>.json, built by npm run update:rankings (see CLAUDE.md for pipeline details). The Yahoo OAuth and ESPN proxy serverless functions in api/ deploy to Vercel; everything else is a static site on GitHub Pages at the custom domain. The Vercel functions read FRONTEND_URL, the Yahoo client id/secret, and an optional VITE_SENTRY_DSN from env; see CLAUDE.md for the full list.

Docs

• CLAUDE.md — architecture, deployment, and contributor guide (start here)
• docs/FANTASY_FOOTBALL.md — domain rules, season calendar, platform API behaviors
• docs/DESIGN_SYSTEM.md — the GRIDIRON design language
• docs/API_REFERENCE.md — platform endpoint notes
• docs/archive/ — superseded and historical docs