06 · Mobile · 2023
Vulcan Eleven
50K peak DAU on real money — 60fps on ₹10k Android.
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By Amit Chakraborty — Senior Software Engineer, Kolkata, India · Remote worldwide
At a glance
- Role — Lead Mobile Engineer
- Year — 2023
- Category — Mobile
- Team — Led team of 8 engineers
- Duration — 18 months
- Hard part — Real-money payments + C++ JSI + 50K DAU at scale
The problem
Real-money fantasy sports. 60fps required on ₹10k Android phones or users rage-quit mid-contest — and in real-money apps, rage-quit equals refund requests and chargebacks.
What I did about it
Moved the scoring hot path off the JS bridge — custom C++ JSI modules for ranking and frame-critical logic, Reanimated 3 worklets for gesture, business logic stayed in TypeScript. No cross-bridge allocations during a live match.
The outcome
50,000 peak DAU, 35% transaction growth, zero critical production failures across the 2023 season. Sub-10 ms contest ranking off indexed PostgreSQL; dual payments (Razorpay + Binance Pay) reconciled server-side.
The project that proved React Native can compete with native at scale. 50K real-money users, dual payment rails, and C++ modules that made ₹10K phones feel flagship.
In detail
Vulcan Eleven is a real-money fantasy sports platform. The constraint was brutal: 60fps on ₹10k Android hardware, or users rage-quit mid-contest. In a real-money app, that translates directly into refunds and chargebacks.
The architecture moved the scoring hot path off the JS bridge. Custom C++ JSI modules handled ranking and frame-critical logic; Reanimated 3 worklets owned gesture on the UI thread; business logic stayed in TypeScript. No cross-bridge allocations during a live match.
Dual payment pipeline — Razorpay (fiat) and Binance Pay (crypto) with server-side reconciliation. PostgreSQL indexed queries for sub-10 ms contest ranking. 50,000 peak DAU, 35% transaction growth, zero critical production failures across the 2023 season.
Built with
React Native · C++ JSI · Reanimated 3 · Razorpay · Binance Pay
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