Founding Engineer

About 0TO9

0TO9 is a bank for entrepreneurship, built by and for financial innovators. We provide infrastructure for entrepreneurs ready to start and scale the next generation of financial products and platforms. Founded in 2025, we're already 75+ co-workers across Europe, and growing fast. Our name reflects our mission: from zero to success, from idea to impact, from now to what's next.

The Venture

We're early and in stealth, so here's what we can say: it's a new banking business, separate from anything else in the group, aimed at a market we think is badly served today. The company is already led by a CEO. The customer, the product, and the wedge are what you'll help us find.

What we're not doing is a hiring cycle to backfill a team. You're early enough that the first architecture calls, the first engineering culture, and a good share of the product thinking are genuinely yours.

How We Build

This is the part we'd be lying about if we said everyone does it.

Agentic coding is our default, not an experiment. Across the group, we run a Claude-Code-native workspace:

• Engineering standards loaded as a skill, so agents apply them automatically.
• A git-backed knowledge base that agents read and extend.
• Agent workflows that take a change from branch to reviewed PR.
• An automated reviewer in CI that counts as an approving review on a pull request. In a team of one, that last one matters.

We're not looking for someone curious about whether this works. We're looking for someone who already builds this way - and will push it further than we have.

What You Will Actually Do

• Compress the distance between idea and working software: prototype, put it in front of real people, and let what you learn kill or grow it. Implementation is the fast part of this job; deciding what deserves to exist is the hard part.
• Sit close to the problem, not the backlog: you'll be in customer conversations and in the room where the business model gets argued about. We expect that to change your technical choices, not just inform them.
• Make fast, reversible decisions: simple, boring architecture that can be thrown away. We don't have scale yet, and pretending otherwise is the most expensive mistake available to us right now.
• Set how engineering works here: tooling, workflow, standards, guardrails — for whoever joins after you.

Technical Requirements

Agentic tools help you pick up anything unfamiliar fast - but these fundamentals should already be there:

Cloud & Infrastructure

• AWS-native: ECS/Fargate, S3, least-privilege IAM.
• Container fluency: build, ship, and debug in production.
• Security by default: WAF, encryption at rest and in transit.
• EU data residency: aware of why region matters (eu-north-1).

Architecture

• Microservices & DDD: boundaries by domain, not layer.
• API/event-driven: no shared databases.
• Resilience patterns: retries, backoff, idempotency.
• Clean, SOLID code: safe for a human — or an agent — to extend.

Delivery & Quality

• CI/CD fluency: GitHub Actions or equivalent.
• Test-driven habits: 80%+ coverage, no exceptions.
• Reviewable PRs: small diffs, no self-merges.
• Supply-chain hygiene: dependency & SCA scanning before ship.

Observability & Security

• Structured logging & tracing: CloudWatch, Datadog, or equivalent.
• Zero hardcoded secrets: Secrets Manager or equivalent, always.
• Encryption everywhere: KMS at rest, TLS in transit.

Nice to Have

• Fintech / regulated-industry background: you'll ramp faster.
• Agentic tools as your daily driver: Claude Code, Cursor, or similar.

Who You Are

• Builder, not just coder: you've shipped real products (side projects count) and know the difference between “working” and “done.”
• AI-native: you already lean on LLMs and agentic tools daily and are curious how far that can go — you see them as leverage, not a shortcut.
• Comfortable with ambiguity: you don't need a fully specified problem to start making progress.
• Business-minded: you can hold a conversation about unit economics, customer needs, or go-to-market — and let that shape your technical choices.
• Pragmatic generalist: deep specialization matters less than range and judgment; you can move across the stack as needed.

What Success Looks Like

• Within weeks, not months, you've helped ship a working prototype we can put in front of real users.
• You've established a lightweight, AI-augmented way of building that lets a tiny team punch far above its weight.
• The founders trust you as a thinking partner, not just a pair of hands.
• Whoever we hire next inherits a codebase and a way of working that's simple, fast, and easy to build on.

Find out more at 0to9.com, we'd love to hear from you!