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Chia Kang Jin

Full Stack Developer
Tokyo, Japan | [email protected]
github.com/xiankai | linkedin.com/in/chia-kang-jin-7719b555/

Summary

Senior Full-Stack Engineer with 14 years building and scaling web applications across Japan and Singapore. At Autify (test automation SaaS, 300+ customer companies) I maintain the automation infrastructure, built both products' MCP servers and an LLM-in-the-loop dependency-update pipeline, and run my own engineering through coding agents. Stack depth: TypeScript/React frontends, Ruby on Rails / Node.js backends, AWS infrastructure.

Experience

Senior Full-Stack Engineer

Autify, Inc. — Tokyo, Japan | April 2022 – Present

• Drove data analytics initiatives across the organization's Business Intelligence stack (cost tracking, data governance, incident reporting)
• Created an ETL pipeline (AWS Glue / Python) that processed 20M+ unstructured log records in days instead of weeks for AI self-healing analysis
• Built, as sole author, a fleet-wide dependency-update control plane: self-hosted Renovate as a GitHub App, deterministic rules first, then headless Claude Code grades each bot PR's risk and can auto-fix it on opt-in, with a human always merging; 55 of the repo's 59 merged PRs, grown to 16 managed repositories, replacing the vendor-hosted bot
• Sandboxed the pipeline's AI agents after finding that one write token could reach every managed repository: per-repo least-privilege App tokens, assess and fix in separate locked-down non-root containers, and the signing key behind a protected environment
• Built both products' MCP servers (web and mobile), turning every public API endpoint into an MCP tool; added agent scenario-authoring tools with write guards so an editor save can't silently overwrite an agent's change, and opened the mobile server to any API token behind a per-token rate limit (300 requests/min)
• Built an incident-response bot that posts context and answers on-call questions from 7 read-only MCP sources behind an MCP gateway on ECS Fargate, with read-only enforced by credentials rather than tool flags so a prompt injection can't write; piloted in live incidents, hardening its connections after each one
• Replaced an image-classification model with a deterministic DOM-based resolver, shadow-tested it behind a canary (3,505 decisions, 99.5% agreement where resolved), and recommended retiring the model, which was then removed
• Run my own engineering through a coding-agent loop: 213 of 313 PRs (Jun–Oct 2026) authored through Claude Code sessions in isolated worktrees, independent cross-harness self-review before posting, and 16 skills and 5 hooks I wrote that encode the team's PR process
• Maintained the test automation pipeline for web / mobile automation, serving 300+ companies
• Architected solutions for email delivery and PDF generation
• Debugged native Selenium WebDriver and Chromium internals to stabilize browser automation
• Active development on Chrome extensions for recording and replaying browser actions
• Reduced mobile device wait time by ~50% by pre-warming devices before test execution
• Assisted in building the test automation pipeline for a desktop application; drove development of the scheduling feature
• Deployed a self-serve infrastructure provisioning API (Pulumi) with AWS IAM permission isolation
• Prototyped a natural language AI Agent for mobile test automation (prompt adherence, element location, model selection)

Tech stack: TypeScript, React, Redux, Apollo GraphQL, Electron, Chrome Extension API, Appium, Ruby on Rails, GraphQL, Postgres, SQLite, Github Actions, CircleCI, Jest, Testing Library, Mock Service Worker, RSpec, Playwright, AWS (ECS/EKS), Kubernetes, Pulumi, Terraform, Holistics, Athena, Redshift, Airbyte

Full Stack Developer

Rakuten, Inc. — Tokyo, Japan | Oct 2019 – March 2022

• Coordinated between 4 departments (20+ people) to build an in-house analytics platform with Form Builder, Query Builder, and multi-timezone support
• Helped maintain CI/CD pipeline and supported transition to Kubernetes
• Took ownership of the logging architecture
• Mentored developers and drove productive code reviews
• Improved QA process with automated testing
• Migrated the codebase to TypeScript
• Developed an ESLint plugin for GraphQL linting

Tech stack: React, Redux, MaterialUI, TypeScript, Tailwind, Node.js, GraphQL, hapi.js, MongoDB, Redis, RabbitMQ, Presto, Druid, Elasticsearch, Python 3, Jupyter Notebook, Jest, Cypress, Testrail, Jenkins, Docker, CloudFoundry, Kubernetes, JIRA, Confluence, Bitbucket

Senior Software Engineer

Tectus Dreamlab — Singapore | Apr 2018 – Aug 2019

• Solely maintained a web app for Proceq (non-destructive testing tools) — chart visualizations with Highcharts, geo-analytics with Google Maps, offline HTML reports with jsdom
• Collaborated on the Screening Eagle platform (construction industry management tool): dynamic form builder, PDF rendering with PSPDFKit, 3D rendering with three.js
• Spearheaded integrated testing that brought bugs down to near-zero
• Integrated i18n and implemented a one-click deployment pipeline

Tech stack: React, Redux, redux-saga, ant.design, Storybook, Webpack 4, Flow, Jest, Cypress, Sentry, Gitlab CI, Jenkins, Docker, AWS

Frontend Developer

Spacebib — Singapore | Feb 2015 – Mar 2018

• Built public-facing and internal admin site for a sporting events platform
• Seamless API integration with backend, continuous UX iteration
• Monitored integration tests and dashboard metrics for site uptime

Tech stack: React, Redux, MobX, Apollo, Bootstrap, SASS, JSPM, Webpack 2, TypeScript, Mocha, Selenium WebDriver, Webdriver.io, Browserstack, CakePHP, GraphQL, Jenkins

Full Stack Developer

Pytheas Travel — Singapore | Jul 2012 – Apr 2014

• Built a whitelabel CMS SaaS catering to 50+ travel agents
• Migrated 35K customers, 1K products and 5 clients, preserving DNS and email functionality
• Automated deployment of dev/production servers with Puppet
• Built a proof-of-concept logging framework with Elasticsearch

Tech stack: Codeigniter 2, jQuery, PHPUnit, Selenium Grid, Nginx, Jenkins, AWS, Puppet, CentOS6

Web Developer

Doorstep Luxury — Singapore | Mar 2012 – Jun 2012

• Developed a WordPress e-commerce site for luxury goods
• Built a standalone web-based POS system (webcam scan + receipt printing)

Web Developer

KLIF Media — Singapore | Dec 2011 – Feb 2012

• Built a prototype social media site on Symfony 2

Education

Bachelor of Arts (Psychology)
National University of Singapore | Aug 2008 – Jun 2011
Electives in Programming and Linguistics

Skills

Primary: TypeScript, React, Redux, Node.js, Ruby on Rails, GraphQL, PostgreSQL, AWS, Kubernetes, Docker
Also familiar with: R, Angular, Elm, Rust, Go, React Native/Expo, Python/pandas, Vue 3, C#, C++
AI / agents: MCP servers, headless Claude Code in CI, claude-code-action, Claude Agent SDK, agent sandboxing, Playwright automation, Huggingface
Data: AWS Glue, Athena, Redshift, Holistics
AI-assisted development: Claude Code and Codex CLI daily: skills, hooks, worktree-isolated parallel sessions, cross-harness self-review
Languages: English (Proficient), Chinese (Basic), Japanese (Basic)

Certifications

• Red Hat Certified System Administrator (RHCSA) — ID: 140-241-662
• Algorithmic Toolbox — University of California, San Diego / HSE on Coursera
• Huggingface Audio Course Certificate of Excellence (xiankai123)

Meetup Talks

• Alternative Libraries for React — JSPM and MobX — ReactJS Singapore
• Data-driven development with Flow — React Singapore

Personal Projects

Pre-AI: built without AI coding agents.

• Remote Explorer Pre-AI · being revived with AI coding agents — Android file explorer over Samba (Kotlin / Jetpack Compose)
• Doorbell Detector Pre-AI — ML audio classification to detect doorbell sounds (Python) doorbell_detector
• FFXIVFurigana Pre-AI — C# plugin to display furigana over Japanese in FFXIV chat
• ChatHistory w/ Vector DB Pre-AI — Import old chat history with semantic search via vector DB chat-history vector-database
• Triple Triad V2 Pre-AI — Rust experiment replicating FFXIV card game logic triple-triad-ai
• XIVAnalysis Pre-AI — Collaborative combat performance analyzer for FFXIV (React, SemanticUI) xivanalysis/xivanalysis
• Pokémon Go Map Pre-AI — Local map tracking EX-raid predictions, serving 3K+ users (TypeScript, MobX, Leaflet, d3.js, Mapbox/OSM) sg-pokemongo-ex-raid-map
• Triple Triad Pre-AI — Multiplayer FFXIV mini-game via WebRTC (peerjs, redux-observables/RxJS) triple-triad-solver
• Web Crawler Pre-AI — Disney Store crawler notifying 15 subscribers of new stock (cURL, Redis, Mailchimp) Disney-Store
• Discord Bot Pre-AI — Web crawler over 10K+ pages with job queue (phantomjs, Redis, Node.js) pusheen-the-fc-helper
• Server Administration Pre-AI — Managed VPS for bots/websites; migrated 6 times across Linode/AWS/Digital Ocean with Puppet/rsync/mysqldump at 100% uptime