Abbeal

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Tokyo · Contractor · Senior (6-9 yrs)

Lead Frontend Engineer — Digital Bank, Tokyo

Own the customer-facing web app of a from-scratch digital bank in Tokyo: greenfield React + TypeScript architecture, strong FP and type-driven culture, scale the frontend as the product grows.

  • React
  • TypeScript
  • TanStack
  • Effect-TS / FP
  • REST / OpenAPI
  • Fintech
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The context

Our client is launching a new digital bank in Tokyo (joint venture between a leading Japanese FinTech and a major banking group), applying for a full banking license. B2B-first: small and medium businesses open and manage their accounts fully online — KYC onboarding, dashboards, payments, contract signing, statements — with no physical branch. The frontend is greenfield: today's small team focuses on the internal ops dashboard, and the customer-facing web app is still to be built. That is where you come in.

Your mission

  • Own the customer-facing web app from day one: architecture, patterns and first lines of code on a greenfield
  • Set the foundations of a maintainable monolithic frontend consuming microservices over REST / OpenAPI
  • Establish state-management standards: clear separation of server state and UI state, single source of truth
  • Drive a strong typing culture: strict TypeScript, domain modeling as types, functional programming patterns
  • Build testing from component level to E2E with an embedded QA team; quality gates in CI
  • Lead and ship solo at first, then help scale the frontend team to 3-6 engineers

The stack

  • React + TanStack (Query, Table, Router) — deliberately no Next.js
  • Strict TypeScript, functional programming, domain modeling as types (Effect-TS under evaluation)
  • Monolithic frontend over REST / OpenAPI microservices; AWS + Kotlin backend
  • AI-assisted engineering (Claude Code used daily), Figma handoff
  • Desktop-first web app; native mobile planned later

The profile

  • Senior frontend engineer / architect with large-scale React + TypeScript production experience
  • Comfortable owning a greenfield solo, then mentoring as the team grows
  • Real affinity for functional programming and type-driven domain modeling (Effect-TS a plus)
  • Fintech or regulated-product experience is a strong plus
  • Fluent English (international engineering team); Japanese not required

The process

Two conversational interviews in English with the engineering manager (the second with one more team member). Feedback within days — this contract role moves fast.

Apply

Lead Frontend Engineer — Digital Bank, Tokyo