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ethan-k - Overview

Hi there, I'm Eunseok Kang 👋

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🚀 About Me

Versatile and results-driven full-stack engineer and tech lead with over 10 years of experience building scalable, production-grade systems. Proven ability to ship quickly in fast-moving environments, with deep expertise in backend (Java, Go, Kotlin) and frontend (React, TypeScript) development.

  • 🌱 Strong track record in leading teams, designing distributed architectures, and optimizing CI/CD pipelines
  • 🎯 Led engineering initiatives that improved user connection rates by 20% and reduced API costs by 20%
  • 🌍 International experience across South Korea, Germany, Singapore, and Japan
  • ☁️ Expert in cloud migration from on-premises to AWS and Kubernetes infrastructure

🛠️ Tech Stack

Programming Languages

Java Go Kotlin Python PHP TypeScript JavaScript

Frontend

React Next.js Redux React Native

Backend & Frameworks

Spring gRPC

Cloud & Infrastructure

AWS Kubernetes Docker Terraform Helm

Data & Messaging

MySQL PostgreSQL MongoDB Redis Apache Kafka RabbitMQ Amazon SQS Apache Airflow Snowflake

DevOps & CI/CD

GitHub Actions GitLab CI Jenkins Ansible

💼 Professional Highlights

🏦 Banksalad (May 2022 - Aug 2025) - Senior Software Engineer (Tech Lead)

  • 🎯 Performance Optimization: Cut external data-provider API costs by 20% via multi-layer caching
  • 📈 Architecture Leadership: Led MyData 2.0 redesign, raising connection success by 20%
  • 🔄 System Resilience: Led transition from synchronous to asynchronous data sync for improved resilience
  • ☁️ Cloud Migration: Led migration initiatives from on-premises to AWS and Kubernetes
  • 👥 Team Leadership: Led 3-person engineering team, introducing Agile and mob programming practices
  • ⚡ Scale: Built large-scale Go microservices on MySQL databases exceeding 4TB
  • 🏗️ Systems Design: Built data sync systems with Go, gRPC, MySQL, AWS SQS/SNS, Kafka, and Redis

🇸🇬 Facebook (Oct 2019 - Dec 2020) - Software Engineer in Test Infrastructure (Contract)

  • 🧪 Test Automation: Developed automated test failure analysis systems for improved debugging
  • 📊 Testing Velocity: Established pipelines for test automation and result analysis
  • 🔧 Framework Enhancement: Enhanced internal E2E testing framework with Jest, TypeScript, React, Hack, and Python

🇸🇬 Gojek (Nov 2018 - Oct 2019) - Software Engineer in Financial Department

  • 💰 Financial Platform: Developed financial platform using Spring (Java), Go, React (TypeScript), PostgreSQL, and BigQuery
  • 🏗️ Microservices: Designed and implemented distributed systems with microservice architecture
  • 📊 Data Systems: Developed high-throughput data distribution system using Kafka and Go

🇯🇵 Rakuten (Apr 2017 - Sep 2018) - Software Engineer in Travel Department

  • ✈️ Travel Platform: Developed travel itinerary system for Japan's second-largest travel booking platform
  • 🔧 CI/CD: Established deployment pipelines using Jenkins, Ansible, and shell scripts
  • 🧪 QA Enhancement: Created test data comparison application using React

🌟 Open Source Contributions

Keycloak Terraform Provider

Active contributor to the official Keycloak Terraform Provider with 4 merged PRs:

  • #1381 - Added authentication subflow data source
  • #1323 - Added support for sub mapper configuration
  • #1382 - Fixed PKCE code challenge method state persistence
  • #1391 - Added missing authorization resource documentation

Contributions span documentation improvements, bug fixes, and feature additions, improving the infrastructure-as-code experience for Keycloak users worldwide.

🎯 Key Achievements

  • 📊 20% Cost Reduction in external data-provider API calls through multi-layer caching optimization
  • 📈 20% Improvement in connection success rates through MyData 2.0 architecture redesign
  • ⚡ 40% CI/CD Optimization of GitLab pipeline through architectural improvements
  • 🏗️ Migration Leadership from on-premises to AWS Cloud and Kubernetes infrastructure
  • 🔧 Full-Stack Expertise across backend (Java, Go, Kotlin), frontend (React, TypeScript), and cloud infrastructure
  • 🌐 Global Impact with experience across 4 countries (South Korea, Germany, Singapore, Japan) and multiple industries (fintech, travel, social media)
  • 💾 Large-Scale Systems handling 4TB+ MySQL databases in microservices architecture
  • 🔐 Enterprise Authentication designed company-wide SSO solutions with advanced access control

📈 GitHub Stats

GitHub Stats

📫 Let's Connect!

I'm always interested in discussing technology, architecture, and engineering leadership. Feel free to reach out!