Fluxpay

Overview

Fluxpay lets friends split bills and small businesses take card payments from a phone. The founders arrived with a prototype that worked on one device and a deadline tied to a launch event — ten weeks out, unmovable.

I rebuilt the app on React Native with a typed API layer, offline-first balances, and biometric login, then carried it through TestFlight, store review, and a monitored public rollout.

Challenge

Money movement leaves no margin for error: failed payments erode trust instantly, and the prototype's happy-path-only logic would have collapsed under real-world edge cases — expired cards, flaky networks, duplicate taps.

Approach

Idempotent payment calls, an outbox queue that retries safely offline, and a full sandbox rehearsal of every failure mode before submission. Store assets and review notes were prepared in parallel, so approval landed on the first attempt.