Jay Koh — Integration Engineer
I work with FinTech startups and enterprise teams who need payment infrastructure that ships in weeks, not quarters.
From enterprise IT to payment systems — I build the infrastructure that moves money across Asia.
What I Do
End-to-end engineering across the full stack, from payment infrastructure to production deployment.
Connect your product to any payment provider, fast. I've wired up 14+ gateways so your transactions flow without downtime or data loss.
High-throughput systems in Go, Ruby, Python, and Java. I build the backend that handles your peak traffic without breaking a sweat.
CI/CD, Docker, monitoring stacks (Grafana/ELK/Zabbix), and cloud architecture. I keep your systems at 99.9% uptime so your team sleeps well.
Clean, responsive interfaces and dashboards that make complex data easy to act on. From admin panels to customer-facing portals.
Career
Process
A straightforward process from first call to production deploy.
Tech Stack
Trusted By
Visa card orchestration platform
14 gateways, 98% faster reconciliation
99.9% SLA infrastructure
2,000+ endpoints automated
Four hours of manual reconciliation, down to five minutes. Fourteen gateways, one unified pipeline. That's what I build.
Proof of Work
14 payment gateways across multiple countries. Each reconciliation cycle: 4 hours of manual work. Discrepancies caught days late. Settlement delays costing real money.
Built an automated reconciliation pipeline in Python. Unified transaction format across all 14 gateways. Real-time discrepancy detection with Slack alerts. Deployed with Docker, monitored with Grafana.
reduction in reconciliation time. From 4 hours to under 5 minutes. 110+ support tickets resolved. Zero settlement discrepancies in production.
Insights
Practical lessons from building payment systems in production.
The two-layer authorization system, tokenization, PCI compliance levels, and five things I learned the hard way.
Read article →Worker pools, fan-out/fan-in pipelines, context cancellation, errgroup patterns, and the concurrency mistakes that cause double charges.
Read article →The three states, Go implementation, configuration tuning, fallback strategies, and monitoring that keeps transactions flowing.
Read article →Contact
Have a project in mind or need a reliable engineer for your team? I'm open to full-time roles, contract work, and consulting engagements.