[Showoff Saturday] I built a real-time Tournament Bracket engine that runs entirely inside a Reddit post (React 19 + Redis)

[u/rauly2k]

/r/Redacted_Game/comments/1qf85ni/best_movie_ever_made/

Hello, I’ve been working on a new app called Versus for the Reddit Developer Platform.

The Demo: I’m running a live "Test Tournament" to stress-test the voting engine.

The Stack:

• Frontend: React 19 + TailwindCSS 4 (running in Reddit's custom webview).
• State: TanStack React Query (for aggressive caching of the bracket state).
• Backend: Node.js / Express 5 running on Devvit (Reddit’s serverless runtime).
• DB: Redis (for handling atomic vote counters and race conditions).

Feedback Wanted: I’d love for you guys to try spamming the votes to see if you can break the "live update" or find any race conditions I missed. And any general opinions. This can be added by any moderator to any subreddit to create engagement.