Taigen Hamada

• Replaced a legacy OCR pipeline with LLM-based document extraction for health checkup records (PDF/images → structured data) at a healthcare SaaS serving Japanese enterprises — substantially higher accuracy.
• Daily production user of Claude Code, Cursor, GitHub Copilot, Codex, and Devin — distilled the know-how into Agent Skills and shared it across the engineering team.
• Spec-driven development: write thorough design docs and context so coding agents deliver the intended result on the first pass.
• LLM tooling: LangChain / LangGraph experience for LLM application development.

AI Tooling ★

Claude Code · Cursor · GitHub Copilot · Codex · Devin · LangChain · LangGraph

Languages

TypeScript · JavaScript (ES6) · Ruby · Python · PHP · Java · + Kotlin, C++11, Lua

Frontend

React · Vue.js · Next.js · Gatsby · Astro · TanStack Start · React Router v7 · React Admin · Storybook · Sass

Backend

Ruby on Rails · Node.js / Express · FastAPI · Django · Spring Boot · CakePHP · Ktor

Databases

PostgreSQL · MySQL / MariaDB · MongoDB

Cloud / Infra

AWS · Google Cloud (Cloud Run) · Docker · Terraform · GitHub Actions · CircleCI · Firebase · Cloudflare

Auth / Others

Auth0 · Twilio · Vite · Webpack · Git

★ = daily production use

1. iCARE, Inc. — Carely (healthcare SaaS)

   Full-Stack Engineer / Tech Lead (PL/PM) · Nov 2022 – Present · Tokyo, Japan

   Vue.js, Ruby on Rails, Python, FastAPI, AWS, PostgreSQL

   • Built an LLM-based document ingestion feature: users photograph or scan health checkup results and the system structures the data — replacing OCR with LLMs for substantially higher accuracy.
   • Led a dedicated AI OCR R&D phase (Oct 2024 – Oct 2025): evaluated models and approaches on real-world documents, then designed and shipped the production pipeline.
   • Designed a configurable rules engine for health-check conditions (e.g., metabolic syndrome criteria); the design was reused by later features, cutting future dev effort.
   • Led AI-tool adoption across the engineering org: Claude Code workflows and Agent Skills, improving team-wide productivity.

2. Legalscape (legal-tech SaaS)

   Independent Contractor — 24 hrs/week · Jun 2024 – Jun 2026 · Remote, Japan

   Vue.js, React, React Admin, React Router v7, Node.js, Express, TypeORM, Python

   • Delivered new features and a frontend redesign while working 24 hrs/week in parallel with full-time employment — a proven part-time remote contractor track record.
   • Full-stack ownership on a 3-person team: frontend and server-side development.

3. FAIR NEXT INNOVATION

   Full-Stack Engineer / Tech Lead (PL/PM) · May 2019 – Oct 2022 · Tokyo, Japan

   Next.js, React, Gatsby, Node.js, Ruby on Rails, Kotlin/Ktor, GCP (Cloud Run), Auth0, Twilio

   • Led 5 web services from inception through design and launch as PL/PM and hands-on engineer on teams of 3–6.
   • Public gym web reservation service (Saga Prefecture): Gatsby + Rails + GCP Cloud Run + Auth0 — designed the entire admin UI/UX myself where no designer was assigned.
   • Real-time video streaming service (Next.js + Kotlin/Ktor); web gacha and web voting services (Next.js + Rails); contact-center internal chat tool (Next.js + Twilio) shipped on a tight schedule with zero critical bugs.

4. Silicon Studio

   C++ Engineer · May 2018 – Apr 2019 · Tokyo, Japan

   C++11, Qt, Visual Studio, in-house rendering engine (Mizuchi)

   • Built a digital dashboard mock tool (Qt) used to prototype next-generation vehicle instrument clusters for a major automaker.
   • Improved driving-simulator graphics: reflected vehicle telemetry (speed, steering angle) in real-time scenes rendered by the in-house engine.

5. Network21

   Software Engineer · May 2016 – Apr 2018 · Tokyo, Japan

   Java, Spring, Objective-C, Python, Scrapy, Selenium

   • Developed an iPad/iPhone POS register application: Java/Spring backend + Objective-C iOS app.
   • As main programmer, built a web scraping tool that detects cross-site-request vulnerabilities — launched as a new business line with significant early revenue.

Open to contract work, AI evaluation projects, or a quick tech chat: