Full Stack Developer

  • Tokyo
  • Partial Remote
  • Full-time
  • August 27, 2025
Conditions
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¥7M ~ ¥10M /yr
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Apply from Anywhere 👍
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Relocation to Japan 👍
(Overseas visa sponsorship supported)
Requirements
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Language Requirements
Japanese: Not Required 👍
English: Business Level
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Minimum Experience
Junior or above

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.

Jamm enables online customers to make digital payments directly from their bank account. Their service is compatible with over 300 financial institutions, including major Japanese banks.

View Jamm's company page

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Full Stack Developer at Jamm
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