Rally

Overview

Rally turns finding a place to play into a game of its own. Every tennis, pickleball, badminton, and soccer court sits on one live map, and the answer to "is it free, busy, or full right now" comes from the players standing on the court, verified by GPS. Log a check-in, add a court that is missing, or confirm someone else's, and you earn XP, a currency called Aces, levels, streaks, badges, and a spot on the seasonal leaderboard. Think of Strava's map meeting a crowdsourced court directory, built on open data and owned by no single map vendor.

What I Built

Rally is a mobile-only app backed by a swappable, self-hostable stack:

• Expo and React Native app for iOS and Android, with a MapLibre map, drag-to-place court creation, and a fullscreen picker, wired end to end and typechecked clean.
• Supabase backend on Postgres and PostGIS: the spatial schema, RPCs, the XP and Aces economy, crowdsourcing with proof-of-presence, rate limits, and row-level security on every table, all covered by a green test suite.
• Cloudflare Workers as the rally-api proxy the app always talks to, so the backend can be swapped without an app rebuild, plus R2 for photos.
• Open data seeding from OpenStreetMap through the Overpass API, with crowdsourcing filling the gaps.

Highlights

• Live free, busy, or full court status with surface, lights, price, and hours on one map.
• Crowdsourced court adds that publish only once two nearby players confirm on-site, so no photo spam.
• Proof-of-presence check-ins by GPS or a court QR code keep the map honest.
• A full gamification layer: XP, Aces, levels, streaks, earned badges, quests, and Local, Friends, and Global leaderboards.
• Games and groups that auto-fill open slots with nearby players, plus push notifications and deep links.

Full Write-Up

I broke down the data model, the proof-of-presence design, and the anti-gaming rules in a dedicated post: Building Rally: A Live, Crowdsourced Court Map That Stays Honest.

Screenshots

See it at rally.ahnafnafee.dev.