Haku Chen

Nobody assigned my best work.

Frontend Engineer · Tokyo, Japan

Frontend engineer in Tokyo. Four years of finding the problem nobody had picked up yet — performance, build pipelines, design systems — and shipping the fix.

See my workOr get in touch

Selected work

Captured 2026-09

Car Rental Japan

Oct 2025 – Present · Frontend lead — architecture, environment setup, implementation.

Released in January 2026 and profitable from the first month, on a maintainable delivery foundation. Development is ongoing.

A new business line requiring integration of multiple rental car providers with inconsistent response formats, plus a scalable delivery foundation built from scratch.

  • Next.js
  • TypeScript
  • GitHub Actions
  • Turborepo
  • pnpm workspace
  • Docker
  • +2
A shared design system sits between the Figma library and the code components, and feeds three productsFigma librarycode componentsshareddesign systemproductproductproduct

Shared UI Library & Design System

Jan 2023 – Jan 2024 · Lead — initial setup, technology selection, design direction, rollout support.

The design team could work from a shared Figma component library while the frontend team implemented matching components — consistent UI/UX with substantially less duplicated code. The library was in production use before I left, and other members kept extending it.

The company's first cross-project design system, built to unify styles and UI across multiple products and to give the design team a shared component library.

  • TypeScript
  • React
  • Nx
  • Lerna
  • pnpm workspace
  • Rollup
  • +5

All work →

Skills

Core — I use these daily and can talk through the trade-offs
Git / GitHubTailwind CSSNext.jsReactHTML / CSSJavaScriptTypeScript
Used on production projects
FigmaBFFREST APIsReact Nativestyled-componentsSassReact Hook FormReduxReact QueryZustandNginxDockerESLintpnpm workspaceTurborepoGitHub Actions
Used earlier in my career
StorybookCypressJestLernaNxtsupRollupViteWebpack

Experience

  1. Inbound Platform

    Frontend Engineer

    Jul 2025 – Present · Tokyo, Japan

    A Tokyo-based travel and digital services company enhancing the experience of international visitors and foreign residents in Japan. In-house development of transport-related web applications.

    • Adapted the organization's monorepo strategy and CI/CD workflows to the products I own, redesigning both to accommodate differing architecture and backend integration requirements.
    • Maintaining and modernizing the existing Highway Bus platform, proactively proposing architectural refactors to resolve longstanding technical debt.
    • Improved mobile performance score from 36 to 85 for the Shinkansen platform through targeted optimization.

  2. AsiaYo

    Frontend Engineer

    May 2024 – Jun 2025 · Taipei, Taiwan (Full Remote)

    In-house development of web and mobile applications for travel accommodation booking.

    • Led SEO and page speed optimization initiatives, reducing FCP/LCP by 4–10 seconds and improving SEO index coverage.
    • Rewrote the legacy affiliate partners SDK library, additionally migrating it to TypeScript on my own initiative; eliminated inconsistencies in affiliate ID tracking and conversion attribution.
    • Implemented member authentication flow optimization across three codebases — React Native, Next.js, and React — increasing new registration conversion rate by 0.13%.

  3. Lion Travel (Lion Information)

    Frontend Engineer | Assistant Team Lead

    Jun 2022 – May 2024 · Taipei, Taiwan

    The IT arm of one of Taiwan's largest travel agencies, developing systems across B2C, B2B, and internal ERP platforms.

    • Promoted to Assistant Team Lead within one year, overseeing technical decision-making and cross-team coordination across 4 product teams, each led by a team lead managing 1–2 engineers.
    • Took ownership of the technical interview process, assessing candidates' technical fit for the engineering team.
    • Spearheaded the company's first cross-project Design System, unifying UI/UX collaboration between design and engineering teams.

About

I studied hospitality management and thought I wanted the kitchen. A month of part-time work at a Japanese restaurant told me otherwise. Looking for something else, I taught myself UI/UX, took a JavaScript course almost by accident, and found the work genuinely interesting for the first time.

There was no network, nobody nearby who knew the field, and not much money — so I found what I could and worked it out myself. That is where the habit comes from, and I still take the unfamiliar option when one is on the table.

Haku Chen

Languages

Traditional Chinese
Native
English
TOEIC 895 — business proficiency
Japanese
JLPT N2 — conversational and business communication

Contact

Open to interesting work and collaborations — anywhere in the world.