SubSync

SubSync sends you a push notification the moment your specific train has a delay or service change — because by the time the conductor announces it, you already missed it.

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Inspiration

We've all been there — headphones in, zoned out on the subway, and suddenly everyone around you gets up and you have no idea why. The conductor made an announcement, but between the music and the crowd noise, you caught maybe three words. The MTA already publishes every service alert in real time. The data exists. Nobody was putting it directly in commuters' hands at the exact moment they need it. That gap is what inspired SubSync.

How We Built It

SubSync has three layers: Frontend — React Native + Expo. The user picks their train line and station, hits "Track My Train," and SubSync watches the MTA feed for them. Alert cards update in real time, and push notifications fire the second something changes — even when the app is closed. Backend — Python + Flask. The backend hits the correct MTA GTFS-Realtime feed, parses the raw protobuf binary data, and filters alerts down to only the user's specific station and line. It compares the current alert state to the last known state — and only notifies when something actually changes, so users are never spammed.

What we learned

Scope is everything at a hackathon. We went through three completely different ideas before landing on SubSync — and the best decision we made was cutting everything that didn't directly solve the core problem. Sometimes the winning idea is the most focused one, not the most ambitious.

What's next for SubSync

Phase 1 — What we built today Real-time push notifications for your specific station and line. The second something changes about your commute delay, service change, skipped stop you know about it before you even reach the platform.

Phase 2 — Smarter, predictive alerts Using historical MTA pattern data to predict delays before they're officially announced. Instead of reacting to problems, SubSync warns you ahead of time. "Your usual A train has a 70% chance of delays right now leave 10 minutes early."

Phase 3 — Full MTA integration + city expansion SubSync becomes native to the MTA ecosystem built into the official MTA app, station screens, and kiosks. Then we expand beyond NYC to any city running a public GTFS-Realtime feed. London. Chicago. LA. Same problem, same solution, every city.

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