Minatomirai Station | Full-Stack Engineer @ AI startup

Role overview

As a Full-Stack Engineer, you will build the customer-facing console and developer experience: onboarding, model catalog, playground, keys/projects, usage dashboards, request logs, and “debuggability surfaces” that reduce support burden and build trust.

This team will work closely with the control plane, serving, and infrastructure teams to ensure the console reflects real platform behavior (streaming, timeouts, rate limits, capacity) and that customer workflows are self-serve wherever possible.

Responsibilities

• Build the web console end-to-end: org/project management, API keys, model catalog, endpoints/tier configuration, and customer self-serve workflows.
• Deliver a high-quality playground: real streaming behavior, parameter editing, model switching, presets, and “copy as code” snippets to accelerate integration.
• Build strong debugging UX: request logs, correlation/request IDs, error attribution, latency breakdowns (TTFT vs decode), and trace/log views where available.
• Build usage and cost visibility: usage charts, per-model breakdowns, rate-limit/quota visibility, and billing/credit status surfaces (in partnership with the control plane team).
• Improve onboarding and docs: quickstarts, examples, SDK patterns, clear error messages, and “first request in minutes” flows.
• Partner with the control plane team: design customer-facing workflows for quotas, limits, tiers, and dedicated endpoints with safe guardrails and clear UX.
• Partner with serving/infra teams: ensure telemetry is reliable enough to show customers, and expose the right signals for debugging and trust.
• Build internal operator/admin tooling: safe customer configuration actions, support workflows, and audit-friendly operations where needed.
• Quality and polish: performance basics, accessibility, consistent UI patterns, stable state management, and pragmatic iteration speed.
• Close the feedback loop: collect customer pain points, reduce friction, and ship product improvements quickly.

[Employment Type]
Full-time employee
*Probationary period: 3 months

[Salary]
Annual Salary: ¥6,500,000 - ¥10,000,000
Monthly Salary: ¥541,666 - ¥833,333 (Monthly Base Salary: ¥541,666- ¥833,333)
■Salary Increases: Available

[Working Hours]
9:00 AM - 6:00 PM (60-minute break)

[Work Location]
Queen's Tower A, 10th Floor, 2-3-1 Minatomirai, Nishi-ku, Yokohama, Kanagawa Prefecture, 220-6010
■Access: 7-minute walk from Sakuragicho Station (all lines), direct access from Minatomirai Station (Toyoko Line, Minatomirai Line)
■Non-smoking workplace
■Changes to work location: Company-designated offices
■Transfers/Secondments: None

[Holidays and Leave]

120 days off per year Days
Full two-day weekend
Annual paid vacation (minimum 10 days after the seventh month of employment)

[Benefits]
Partial transportation allowance (up to ¥15,000 per month)
Social insurance (health insurance, employee pension insurance, employment insurance, workers' compensation insurance)
Overtime pay: Standard overtime pay

Requirements

• 5+ years building production web products (React/TypeScript) plus comfort collaborating on backend contracts.
• Strong product taste and developer empathy; you care about “it just works.”
• Ability to translate platform complexity into clear, trustworthy user-facing experiences.
• Strong engineering habits: testing, performance basics, clean interfaces, pragmatic iteration speed.
• Strong written communication—docs and error messages are part of the product.