Vpon AI Big Data Group, Senior Software Engineer, Jul 2025 ~ Apr 2026

Owned a high-traffic core SSP advertising system operating for more than 10 years and processing over 80 million requests per day, responsible for core feature development, maintenance, and system improvements.

Key Responsibilities and Achievements
SSP System Evolution and Microsoft Xandr Integration
• Developed and maintained core backend features for the SSP system, including core ad request processing, external platform integrations, and related system functionality.

• Completed Microsoft Xandr integration with the existing system and deployed it to production.
• Adopted the IAB OpenRTB Library as the standard for constructing OpenRTB requests across DSP implementations, reducing the maintenance cost of custom models.
• Refactored the single-DSP request flow into asynchronous multi-DSP processing, using Hystrix to manage overall wait time, service-specific timeouts, fault isolation, and cancellation of timed-out requests.
• Established observability for the Xandr integration using Prometheus and Grafana.
• Reworked the existing Infinispan caching architecture using Caffeine and Couchbase, and introduced Protobuf to reduce data size and serialization overhead, successfully reducing API latency variability.
• Upgraded Spring Framework from 3.0.5 to 3.2.18 and completed compatibility adjustments required to support asynchronous multi-DSP processing.

Technologies
Java, Spring Framework, Hystrix, Couchbase, Caffeine, OpenRTB, Protobuf, Prometheus, Grafana, JUnit, MySQL, K6

One Step Technology Ltd. Co., Go Backend Engineer, Dec 2023 ~ Nov 2024

Served as the sole backend engineer for www.onestep.place, independently responsible for feature development, architecture improvements, third-party service integrations, testing, and system maintenance across two major projects. Primary technologies included Go, Gin, GORM, MySQL, and Redis.

Key Responsibilities and Achievements
• Refactored two major projects following Clean Architecture principles, reorganizing module responsibilities and dependencies to improve testability and maintainability.
• Integrated third-party payment services and implemented refund workflows, supporting partial refunds, asynchronous refund-result processing, and payment/refund status synchronization.
• Implemented search functionality by building an inverted index in Redis and combining it with MySQL full-text search, supporting keyword search, filtering, and pagination.
• Built Google Calendar synchronization using Redis queues and long polling to synchronize booking slots, supporting centralized management of online and on-site reservations.
• Designed a reusable Price Model to support different partner pricing schemes, reducing the impact of partner-specific requirements on core business logic.
• Developed hierarchical tagging to support multi-level content categorization and management.
• Built unit tests using Go testing, mockery, and go-sqlmock to reduce risks from feature changes and refactoring.

Technologies
Go, Gin, GORM, Redis, MySQL, Google Cloud Platform (GCP), GitHub Copilot

Cherri Tech Inc., Senior Java Developer, Nov 2021 ~ Nov 2022

Worked on TapPay payment services, integrating banks and payment providers, developing transaction, capture, and refund features, and handling transaction issues escalated by frontline operations.

Key Responsibilities and Achievements
• Integrated banks and third-party payment services, handling API requests, response formats, and transaction status mapping.
• Developed and maintained capture workflows, including scheduled captures and manual capture operations during production support.
• Resolved partial-refund concurrency issues across multiple bank integrations using Idempotency Keys and retry mechanisms.
• Investigated transaction issues escalated by frontline operations, including transaction failures, status inconsistencies, captures, refunds, and reconciliation.
• Wrote unit tests using JUnit, Mockito, and PowerMock, and participated in code reviews.
• Collaborated with product, customer service, operations, and engineering teams to clarify payment issues and requirements and implement system changes.

Technologies
Java, Spring Boot, JUnit, Mockito, PowerMock

Mirror Media, Backend Engineer, Apr 2020 ~ Sep 2020

• Developed CMS features using KeystoneJS 5, Draft.js, Node.js, React.js, PostgreSQL, and GraphQL.
• Refactored Python data import functionality and integrated Elasticsearch clusters to improve search performance for the media website.
• Maintained and extended backend services built with Go and Gin.
• Automated data processing using Python scheduling tools.
• Maintained CI/CD and GitOps deployment workflows using Kubernetes, Helm, Flux CD, Drone CI, and Docker for service deployment and environment management.
• Configured GCP infrastructure and Nginx to support service deployment and environment management.

Technologies
Node.js, JavaScript, React, Python, Kubernetes, Docker, Google Cloud Platform (GCP)

Hannlync Technologies Inc., Java Developer (Contract), Sep 2019 ~ Mar 2020

Cathay United Bank (5 months)
• Developed and maintained APIs using Spring Boot.
(Left after contract completion.)

NewPOS Tech. Corp., Senior Java Developer, Oct 2017 ~ Sep 2018

• Developed web-based B2B SaaS applications, including Online Fitness Course Booking, POS Management, and Payment Gateway Reporting/Dashboard systems.
• Maintained a Central Authentication Service (CAS) using OAuth2.0 for secure user authentication.
• Applied Clean Architecture principles to deliver maintainable and testable modules.
• Designed and optimized relational database schemas in compliance with Third Normal Form (3NF).
• Enhanced API performance through Java concurrency, SQL tuning, and code refactoring.

Technologies: Java 8, Play Framework, EC2, RDS, Memcached, S3, IntelliJ IDEA, Git, MySQL, MongoDB, Swagger, Docker, JUnit, EBean, JPA

urAD Co., Ltd., Applications Engineer, Jun 2015 ~ Dec 2016

Data Management Platform | Backend Engineer
• Developed RESTful serverless APIs for a real-time statistics dashboard using Node.js, Serverless Framework, AWS Lambda, AWS API Gateway, AWS RDS, and MySQL.
• Optimized API performance through SQL tuning and Async module implementation, reducing average response time by 40%.
• Designed an early workflow for clickstream data collection using GTM, JavaScript, and PHP, improving data accuracy.

Additional Projects
• Published a shopping-cart application built with Swift and Storyboard.
• Enhanced a slot machine game using Cocos2d, improving functionality and user experience.
• Created tracking SDKs in Objective-C and Swift, ensuring seamless integration with advertising platforms.
• Built web services with PHP, Laravel, and MongoDB.

Webi & Neti Internet Service Inc., iOS App Developer, Sep 2013 ~ Sep 2014

• Developed native iOS applications for iOS 7 using Objective-C and Storyboard, ensuring optimal performance and user experience.
• Integrated a C-based filesystem and UDP/IP networking for efficient and reliable remote file access (RFA).
• Enhanced third-party C-based filesystem functionalities to improve stability and performance.
• Designed and implemented RESTful APIs with Java Servlet to support application features.
• Published two iOS apps: WiFi@SDCF and WIFI-ShareDisk.