Senior Backend Engineer at PayPay - Peer to Peer Team (2025-10 – Present)
- Own backend services and API design for peer-to-peer payments across a distributed microservice architecture (Kotlin / Spring Boot / Aurora MySQL / Redis / Kafka / Kubernetes).
- Architected and shipped cross-platform P2P payment integration (send money, request money, bank sync) for the LINE super-app — designing LINE-specific API contracts, idempotency guarantees, and risk-check flows across three microservices with zero regression on existing PayPay native flows.
- Led backend investigation and implementation to scale P2P social network friend limits 25× (200 → 5,000 per account) — benchmarked Aurora MySQL across 200K+ relationships confirming sub-linear index scaling (P99: 65ms → 178ms), validated RDS headroom at 0.8–1.4% CPU and 99.994% buffer cache hit ratio, and authored full design documentation covering schema, cost projections, and phased rollout plan.
- Diagnosed and resolved a cross-team recurring OutOfMemoryError in a long-running Kafka consumer service (campaign-transaction-propagator) — traced root cause to unscraped Micrometer metrics accumulating in JVM Old Gen heap due to a Prometheus whitelist mismatch; surgical 2-line fix reduced metric growth rate from 52/hour to 0.11/hour, validated over 20+ hours and 19.85M messages with zero OOM recurrence.
- Leveraged LLM-powered engineering tools and agentic workflows to accelerate cross-service API exploration, observability analysis, PR triage, and design-to-code execution, reducing debugging and development turnaround time.
- Coordinated API contracts, error code mappings, and backward-compatible rollouts across dependent teams (frontend, platform, downstream services).
- Mentored junior engineers on service ownership and production readiness; created operational runbooks to improve incident response.
Backend Engineer at PayPay - Payments and Cashback Team (2024-01 – 2025-09)
- Designed and implemented backend systems for points based payment processing, improving transaction throughput and overall system scalability.
- Built payment debit, refund, reversal, partial capture, and re authorization flows to ensure accurate financial reconciliation and safe recovery from failures.
- Decoupled merchant cashback accounts from tightly coupled services (CTP & CTI), reducing architectural complexity and enabling faster feature rollout.
- Conducted performance testing and failure scenario documentation, identifying bottlenecks and improving fault tolerance.
- Delivered multiple production releases with thorough staging validation and post-deployment monitoring, maintaining high release success rates.
- Investigated and resolved critical production issues related to payment failures and wallet reconciliation.
- Improved service performance, reliability, and operational cost through database tuning, connection optimization, and better observability.
- Mentored junior engineers, fostering best practices in system design, performance testing, and monitoring.
Senior Software Engineer at ZET (ONECODE) (2022-10 – 2023-11)
Led backend development for a customer loyalty platform, improving long-term user retention.
- Designed state machines for user onboarding and credit score retrieval, increasing conversion rates.
- Led a team of six engineers to revamp core backend services within three months.
- Migrated 160M customer records, ensuring smooth transition and data consistency.
- Reduced MySQL CPU usage from 98% to 20% and system error rate from 10% to 1%.
Software Development Engineer at ZET (ONECODE) (2022-01 – 2022-10)
- Implemented growth and onboarding features including scratch cards and credit score integrations.
- Optimized customer acquisition workflows to reduce operational costs.
Software Development Engineer and Research Intern at Jio and Philips (2021-01 – 2021-12)
- Built customer segmentation algorithms and optimized machine learning pipelines, reducing processing time by approximately fifty percent.
