PropBattles

Inspiration

We’ve always been avid sports fans — from heated fantasy drafts to risky parlays on game day. That passion inspired PropBattles, a mobile app that merges the excitement of fantasy sports, the strategy of player props, and the fun of trash-talking with friends.

What We Built

PropBattles combines three major experiences:

Season Draft: Instead of building a roster, players draft the exclusive rights to wager on specific player props for the entire season.
Banter Page: A social feed where leagues can talk smack, share memes, and keep the competition lively all season long.
Battle Mode: Real-time, head-to-head prop betting during games, where friends can instantly challenge each other and see results update live.

How We Built It

Frontend: Developed with Expo Go (React Native) to deliver a fast, cross-platform mobile experience.
Backend: Built on Supabase for user authentication, persistent storage, and real-time database subscriptions.
Data Integration: Leveraged ODS and ESPN APIs to fetch player data and live prop lines, powering both the draft and battle modes.
Real-Time Features: Used Supabase’s live channels to keep drafts synchronized, battles resolved instantly, and balances updated without delay.

Challenges We Faced

Season Draft Mechanics: Building a fair, snake-style draft with exclusive rights for the season required careful transaction design to prevent duplicate picks and enforce timers.
Battle Mode with Live Data: Mapping fast-changing ESPN stats to active wagers was tricky — handling latency, ensuring fairness, and preventing mismatched results were major hurdles.
Concurrency Across Leagues: With multiple leagues running drafts and battles simultaneously, we had to design atomic database operations and consistent real-time subscriptions to avoid conflicts.

What We Learned

Through PropBattles, we learned how to:

Architect real-time mobile experiences on top of Supabase.
Combine fantasy-style exclusivity with betting logic in a seamless way.
Integrate third-party sports APIs into highly interactive game mechanics.
Engineer around the challenges of latency, concurrency, and fairness in competitive systems.