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Full Stack Developer

Japandev

Jamm

Tokyo Employment type not available Deadline not available

Job description

About us

We’re an early stage fintech company building a better way to pay. We’re a small team where engineers work closely with product, design, and business, and where clear thinking and clear communication matter as much as the code itself.

What you’ll work on

Features end to end, from the user interface down to the services and data models behind them.

Turning loosely defined problems into clear plans, and getting the right people aligned before building.

Writing design proposals and technical documents that help the team make good decisions.

Deciding when something should ship quickly and when it deserves a deeper redesign, and explaining that trade-off to technical and non-technical colleagues alike.

Spotting tech debt early and making the case for addressing it.

Who we’re looking for

You’ve worked as an engineer in a professional setting and can talk in detail about systems you built, how they held up over time, and what you learned from them.

You explain complex ideas simply, in writing and in conversation. People come to you when they need something clarified.

You ask for feedback on your work, take it seriously, and can point to times it changed your approach.

You pick up unfamiliar tools and domains quickly, and you’re comfortable being productive before you know everything.

You can take a goal and run with it independently, while keeping others informed without being asked.

You’re comfortable across the stack. Leaning frontend or backend is fine.

Nice to have

Experience in payments, banking, or other domains where correctness is a priority.

Experience at an early stage company, or a clear reason you want to be at one now.

Business level Japanese (N2+)

Our stack

Frontend: TypeScript/JavaScript, SvelteKit, Swift, Kotlin, React 

Backend: Go, ConnectRPC/Protobuf, Temporal, PostgreSQL

Infrastructure: AWS, Terraform

You don’t need experience with all of these. We’d love to talk with someone who has gone deep on a few and learns the rest quickly.

What it’s like here

Direct access to decision makers. Good ideas get heard and acted on quickly.

Real ownership of your work, with support from the team when you need it.

A culture of open, honest feedback in both directions.

How to apply

Along with your resume, send a short written note about a technical problem you solved at work. Tell us what the constraints were, what you tried that didn’t work, and what you’d change today. We’d love to hear this in your own words, since how you explain your thinking matters to us as much as the problem itself.