Work · Build · Architect
Rebuilding a subscription billing engine that kept creating cycles wrong
~40% fewer recurring billing errors across three production Next.js applications serving 2,000+ active subscribers, plus a reconciliation portal that gave finance ~10 hours a week back.
- Role
- Senior Tech Lead
- Where
- Flux, Kuala Lumpur
- When
- Apr 2023 to Jul 2025
Context
Flux is a car-subscription startup: plans bundle financing, insurance, tax and maintenance for subscribers and vehicle hosts. I led end-to-end delivery of its three production applications, the customer web app, the backend and the admin console, in Next.js and TypeScript, with a squad of three to five engineers.
The constraint
Subscription billing has edge cases that only show up in production: cycles created at the wrong boundary, proration on plan changes, payments arriving off-platform by direct transfer that the system never saw. Each one became a finance ticket and a subscriber conversation.
What I did
Reworked the subscription and billing engine to eliminate the cycle-creation edge cases. Built a reconciliation portal for off-platform and direct-transfer payments so finance stopped matching by hand. Introduced Metabase across finance, operations and product, and partnered with the CEO and Product on conversion-focused features.
Outcome
Recurring billing errors down ~40%. Subscription conversion up ~15%. Reconciliation saving ~10 finance staff-hours a week. Report turnaround from days to under an hour.