Overview
Hand Me Downs is a two-sided marketplace where ASU students buy and sell used textbooks directly — no fees, no middleman, campus pickup. It's the kind of product where nothing works until both sides show up: sellers need a fast, low-friction way to list; buyers need to browse, trust, and transact. I designed and built the whole thing — the web app, the Postgres data model, the auth and image storage, and the analytics that tell me whether the marketplace is actually breathing.
What I built
- A Capacitor web app — list a book in under 30 seconds with photos, search by title or course code, save listings, and message sellers to arrange campus pickup.
- A Supabase backend: Postgres schema for users, listings and the marketplace funnel, with row-level security and image storage.
- A "Marketplace Health" analytics dashboard in Metabase — 26 SQL-native cards across Growth, Liquidity & Funnel, Supply & Pricing, and two-sided Engagement, fed by a strictly read-only role so reporting can never touch production data.
- Reproducible dashboard tooling — every query is version-controlled and the whole dashboard rebuilds from code.
Why it matters
Marketplaces live and die on liquidity, and you can't improve what you can't see. Rather than guess, I instrumented the funnel end to end — signups, listings over time, the buyer/seller balance — so product decisions ride on honest numbers, not vibes. The dashboard scales automatically as the marketplace grows.
Screens
