Hyunwoo Lee
Backend Developer · 7 years
hyunwoo.lee@example.com
Core strengths
• Cut p95 API latency by 70%+ on 3 high-traffic services
• Split a 9-year-old monolith into 5 services without a single outage
• Built on-call runbooks that lowered MTTR from 55 to 18 minutes
• Mentored 4 junior developers through code review and pairing
Career details
Example Commerce Co. · Platform Engineering Senior Backend Developer
2021-04 – PresentResponsibilities Designs and operates the order, payment and settlement APIs for a marketplace with about 2 million monthly users.
Payment Domain Service Split
2023-02 – 2024-01Technologies Kotlin · Spring Boot · Kafka · PostgreSQL
• Extracted payment and refund logic from the monolith into 2 services with 0 downtime.
• Reduced payment-related deploy time from 40 minutes to 8 by separating pipelines.
• Introduced idempotency keys that cut duplicate charges by 98%.
Order API Performance Overhaul
2022-03 – 2022-10Technologies Java · Redis · MySQL
• Rewrote 3 N+1 queries and added a read-through cache for order lookups.
• Lowered p95 latency from 820 ms to 190 ms at 1,200 requests per second.
• Cut database CPU usage during peak sales events by 45%.
Observability and On-call Setup
2021-07 – 2021-12Technologies Prometheus · Grafana · PagerDuty
• Defined alerts for 14 core endpoints and wrote 6 incident runbooks.
• Lowered mean time to recovery from 55 minutes to 18 within 2 quarters.
Example Logistics Inc. · Delivery Systems Team Backend Developer
2018-03 – 2021-03Responsibilities Built APIs for dispatch, driver tracking and delivery status used by partner shippers.
Real-time Delivery Tracking API
2019-05 – 2020-06Technologies Node.js · MongoDB · WebSocket · AWS
• Built a location ingestion pipeline handling 3,000 driver updates per minute.
• Reduced status-inquiry calls to the support center by 30%.
• Onboarded 12 partner shippers, including Company A, to the public API.
Reason for leaving Moved to a larger-scale platform role
Skills
Languages & frameworks Kotlin · Java · Spring Boot · Node.js
Data & messaging PostgreSQL · MySQL · Redis · Kafka
Infrastructure AWS · Docker · Kubernetes · Prometheus
Certifications
AWS Certified Solutions Architect - Associate · Amazon Web Services 2022-08
Education
Example University
2012-03 – 2018-02Computer Science · B.S. · Graduated