Fintech engineer

Nanzen; Amsterdam; On-site; EUR 70,000 - 100,000; Full time

Job summary

Nanzen is hiring a Fintech Engineer to build the core data model and the integrations that enable trusted payments, ledgers and reconciliations. You’ll design a single canonical representation that external systems map into, and own the boundary where money decisions occur.

You’ll work in a small, highly autonomous team with a strong focus on AI-enabled fintech, bank connectivity, and E-invoicing related workflows. The role is hybrid, based in Amsterdam.

Qualifications

• Experience with payments, ledgers or banking infrastructure and a strong view on idempotency.
• Interest in fintech intersection with AI and ability to translate business needs into data models.
• Proven ability to design durable data models across multiple integrations and vendors.
• Capability to build adapters and maintain a stable canonical representation of transactions.

Responsibilities

• Own the model representing transactions between partner systems and what actually happened.
• Build and maintain bank connectivity, Open Banking and payment initiation integrations.
• Design auditable, reconcilable data structures that survive vendor changes.
• Develop adapters to map external systems into a single canonical representation.
• Collaborate with finance teams to ensure accurate settlements and reconciliation.

Tools

Python

PostgreSQL

FastAPI

Terraform

AWS

GCP

TypeScript

Job description

What is Nanzen

Nanzen is disrupting B2B by bringing agentic workflows to finance operations, automating critical, trust-sensitive flows that still run on emails, spreadsheets, old databases, manual approval chains and basic wire transfers.

We are ambitious, we are building Nanzen to be an era-defining company, where there's a clear before and after in B2B commerce.

The Nanzen team

Nanzen's philosophy is to bring the smallest team of the greatest people that cover maximum footprint.

We prefer in person but we do hybrid. Life can be better if you can make the best of both worlds. The days we are not sitting next to each other we miss the speed of a whiteboarding session and the good vibes.

You need to have the ambition to work on something small that can change the world. This requires your attention and love. It's about caring, not sucking your life into non-existence. We have families and we intend for our kids to see their parents but this is not a 9 to 5 job at Dunder-Mifflin.

Trust is everything. At Nanzen we base our relationship on transparency, autonomy and accountability (= allergic to BS).

The Fintech Engineer role

Finance runs on other people's systems. Every one of them has its own format, its own idea of what a transaction is, and its own way of being partially wrong. Making that coherent is most of the work, and it's the part that decides whether anything built on top can be trusted.

The architectural bet is that the model outlives the integrations. Providers get swapped, companies pivot, a market turns out to work differently than the documentation claimed. What has to survive all of that is one coherent representation that every external system maps into so that adding a country, a partner or a customer is an adapter, not a rewrite of everything above it.

What you own

The model. The representation of what two companies agreed and what actually happened between them, and the discipline that keeps it correct as it grows: auditable, idempotent, reconciling to the cent, and reconstructable years later.

The boundary where a decision becomes money. Nanzen builds agents that take real finance actions, at a volume and granularity no team does by hand. That only works if the layer beneath them is exact. You own that boundary, and you'll shape it alongside the people building the agents.

Reconciliation as a product surface, not a batch job. Matching, cash application, exceptions, short payments, credits, and specifically what happens to the things that don't match, which is where every finance team actually loses its afternoons.

Bank connectivity, Open Banking and payment initiation. Instructing payments through bank connectivity and partner providers, the consent and authority models behind them, and reading status and statements back so we know what actually settled.

The substrate the next decade runs on. E-invoicing networks and standards (Peppol, EN 16931, the national clearance platforms, ISO 20022 across initiation, reporting and remittance) are turning money movement between companies into something structured and machine-readable. That's the blueprint for a better way of paying, and working fluently in it is a large part of this role.

ERP and system-of-record integration. Pulling orders, invoices, receipts, payments and credits out of ERPs, CRMs and accounting systems into the model.

Partner selection and orchestration. Choosing providers, integrating them, and keeping the abstraction clean enough that one can be swapped without the rest moving — and that we can choose between them at runtime.

Customer reality. Working closely with finance teams inside their actual close, their actual reconciliation, their actual disputes.

The bar. You set the standard for whoever joins next, and you help choose them. We hire slowly and stay small on purpose.

You’ll probably recognise yourself

• You've worked on payments, ledgers, or banking infrastructure, and you have opinions about double-entry, retries, and reconciling other people's data.
• You are excited about how fintech will intersect with AI and want to build that future.
• You've been on the wrong end of an idempotency bug and you design like it.
• You've built a data model that survived three vendors and a market you didn't plan for or maintained one that didn't, and you know exactly where it broke.
• You've integrated something documented one way and behaving another, and you found out before it cost anyone money.
• You'd rather ship a narrow thing that reconciles than a general one that mostly does.

Probably not for you if

• You need the destination described before you'll start walking. Nobody here can hand you the spec, because the better version of this doesn't exist yet.
• You want to be deep in one thing and served by the other. This role needs someone equally willing to debug a connection pool and to read a payment-message specification until they understand why a field exists.
• You don't think AI will take a real role in finance. You don't have to be a maximalist. Scepticism is welcome and often correct and we encourage grounding. But the premise of the company is that this shift happens.

How we work

Very AI-pilled but anchored in reality. Small team, high trust, no ceremony.

Stack: Python, FastAPI, Postgres, Next.js/TypeScript, Terraform, GCP/AWS