Fernand William

I’m a software engineer who ships production systems end-to-end, from requirements gathering and system design to deployment and maintenance. I use AI-assisted test-driven development with Claude Code and OpenAI Codex to accelerate development while maintaining production-grade architecture, testing, and code quality. Recently, I’ve led end-to-end delivery of a NestJS/React/PostgreSQL portal on GCP that serves as the daily operational hub for 500 sales representatives across Indonesia.

I engineered a write-behind audit pipeline with Redis and NestJS cron workers to batch up to 500 records per flush to PostgreSQL with zero data loss and no API latency impact. I also implemented Redis-backed JWT session management with token rotation and replay detection, plus a custom React video player that prevents unauthorized access to internal video resources. Alongside that, I built a backend actuarial calculation service with proprietary formulas, strict input validation, and regulated audit logs, and I’ve delivered additional customer-facing products like a field sales activity management app built from scratch with Next.js and Supabase, deployed on Vercel with ongoing monitoring and feature support.