Full Stack Developer

Applications: candidates may apply from outside Japan. Visa sponsorship: available. Japanese: Not required. English: Business level. Japan Dev tags: Engineering, Web / Full-stack, Go, React, PostgreSQL.

Full-Stack Developer

About the Role

We’re looking for a Full-Stack Developer who is excited to build scalable, resilient systems and elegant user experiences at an early-stage startup. You’ll own features end-to-end — from design and architecture to implementation and refactoring — while balancing immediate delivery with long-term technical health.

This role is ideal for someone who thrives in a fast-paced environment, has a proactive mindset, and wants to shape both product and engineering foundations.

Responsibilities

• Design and implement new features across frontend and backend.
• Architect systems thoughtfully (DB schema, internal communication, data flows) to enable feature scalability and robustness.
• Take ownership of delivering individual features end-to-end.
• Monitor tech debt and drive proactive refactoring.
• Make smart trade-offs between speed and scalability when implementing features.
• Continuously refine systems to support future growth.

Requirements

Must-Haves

• Full-stack development capability (even if frontend-leaning).
• If experienced, at least 2 years tenure at a single organization is preferred.
• History of internal promotion is strongly preferred.
• Proactive in identifying problems before they occur and taking action.
• High intrinsic intelligence with the ability to make sound short-term and long-term technical decisions.

Preferred Qualifications

• Excitement about working in an early-stage startup.
• Curiosity and enthusiasm for new technologies.
• Experience in the fintech/payments space is a plus.
• Hands-on experience with some of the following:

Frontend Stack

• HTML/CSS
• Tailwind
• Svelte / SvelteKit
• React
• TypeScript

Backend & Infrastructure Stack

• Go (Chi)
• ConnectRPC/gRRC
• Protobuf / Bufbuild
• Temporal
• AWS
• Terraform
• Git / GitHub
• PostgreSQL

Why Join Us?

• Impact from day one: Shape the foundations of both product and engineering.
• Growth opportunities: Be part of a small, ambitious team where your contributions are recognized.
• Challenging problems: Work on complex systems that require thoughtful design and proactive innovation.
• Culture of ownership: We value people who take initiative and push boundaries.