ChiaMin Liu (liuliu)

Backend Software Engineer

About Me

  • Backend / platform engineer with 6+ years across 3-tier systems and AWS/EKS microservices.
  • Operated high-traffic APIs (2.5M+ users, ~10K peak QPS) and led performance work (up to -77% latency, +18% throughput).
  • Own CI/CD, observability, and incident response; prefer simple, measurable improvements over big rewrites.

Skills

Programming Languages

  • Python
  • Java
  • Rust
  • JavaScript
  • PHP

Frameworks

  • FastAPI
  • Spring Boot
  • Django REST Framework (DRF)
  • Vue
  • Actix
  • Laravel

RDBMS

  • PostgreSQL
  • MySQL
  • MariaDB
  • SQLite

NoSQL

  • MongoDB
  • DocumentDB
  • DynamoDB
  • Redis

IaaS

  • AWS (EC2, EKS, ELB, S3, CloudFront, Lambda, SQS, CloudWatch, CodePipeline, etc.)

Misc

  • GitHub Actions
  • Kafka
  • OpenSearch
  • Kubernetes
  • Istio
  • Docker
  • Docker Swarm
  • Nginx
  • Ansible
  • Terraform
  • Helm
  • Swagger
  • Supervisor

Experiences

Backend Software Engineer

Dec 2023 - Present

President Chain Store Corporation(PCSC), Web Portal

  • Built and operated backend services for a web portal (2.5M+ users, ~10K peak QPS) on AWS + EKS.
  • Designed OIDC/SSO identity + session flows and shipped core domain services (membership, access, routing).
  • Led a performance baseline and load-test + tuning cycle for an authorization service; improved critical endpoints by up to -77% latency and +18% QPS; validated 500+ QPS targets.
  • Investigated recurring OOM under sustained load (reproduced via load testing); isolated off-heap growth + Metaspace pressure + a DB bottleneck; mitigated impact with query/index improvements and runtime tuning.
  • Delivered an event-driven video processing pipeline (S3 + MediaConvert + SQS/SNS) with status tracking and async polling.
  • Hardened Python container builds/runtimes (non-root, secrets hygiene) and reduced image sizes by ~58%.
  • Improved release safety and observability: CI quality gates, CloudWatch dashboards/alarms, centralized logs, and audit logging to support ISO 27001.
  • Tech:
    • Languages: Python, Java
    • Frameworks: FastAPI, Spring Boot
    • Datastores: PostgreSQL, Redis, DynamoDB, DocumentDB
    • Cloud/Infra: AWS (EKS, S3, SQS, SNS, Lambda, CloudWatch, MediaConvert)
    • Tooling: Terraform, Helm, Docker, Kubernetes
    • Testing/Perf: k6, Vegeta

Backend Software Engineer

Apr 2020 - Nov 2023
  • Built and maintained REST APIs in PHP (Laravel/Lumen) for the web product and admin portal.
  • Improved API performance by ~20–30% through profiling, refactoring, and query optimization; reduced MySQL hot-path queries by up to 50%.
  • Added PHPUnit coverage for key business logic and kept OpenAPI/Swagger docs up to date for smoother handoffs.
  • Built async workflows with SQS + Lambda (Python/Node.js) for background processing.
  • Integrated LINE Messaging API for user-triggered workflows/notifications; shipped personalized recommendations and improved retention by ~20%.
  • Integrated OpenAI API for a learning assistant chatbot.
  • Operated a 3-tier AWS stack (ALB/EC2/RDS) and owned CI/CD (CodePipeline/CodeBuild/CodeDeploy) plus autoscaling and CloudWatch alarms.
  • Containerized services with Docker, managed images in ECR, and ran deployments via Docker Swarm; reduced image size by ~50%.
  • Improved monitoring and incident response with Slack alerting; reduced MTTD by ~80%.
  • Improved SPA SEO via prerendering.
  • Tech:
    • Languages: PHP, JavaScript, Python
    • Frameworks: Laravel, Lumen, Vue, Nuxt
    • Datastores: MySQL, SQLite
    • Cloud/Infra: AWS (EC2, ALB, RDS, SQS, Lambda, CloudWatch, ECR, S3)
    • Tooling: Docker, Docker Swarm, OpenAPI/Swagger
    • Testing: PHPUnit

Projects

Here are my side-projects.

(RUST) Documentation Embedding - Rust CLI to embed documents and store vectors in Qdrant for semantic search.
(Python3) ChatGPT token usage Calculator - A small tool to estimate token usage for prompts before sending requests.
(Docker) Dockerize Templates - A collection of Docker templates to bootstrap common stacks.

Certifications

AWS Certified Solutions Architect - Associate (SAA)

2023 - 2026
AWS (AWS03666006)

Validates core AWS architecture skills across networking, compute, storage, security, and reliability best practices.

OSS Contributions

My open source software contributions.

actix/examples - Community showcase and examples of Actix ecosystem usage.
openai-cookbook - Examples and guides for using the OpenAI API.
design-patterns-for-humans-zh-TW - An ultra-simplified explanation to design patterns.