Backend Engineer (TypeScript/Nodejs)

Levy Professionals; Amsterdam; On-site; EUR 90,000 - 130,000; Full time

Job summary

Levy Professionals is seeking a Backend Engineer to own and evolve a secure API platform in a fintech environment. You will design, implement, and deploy partner-facing services using TypeScript/Node.js on AWS, focusing on API quality, security, and scalability.

You will drive API design, contribute to OpenAPI specifications, and work with a senior team to ensure robust, production-ready delivery and strong observability across the system.

Qualifications

• Hands-on backend development with TypeScript/Node.js.
• Strong REST/JSON API design and OpenAPI mindset.
• Hands-on AWS experience with containers, queues, managed databases, secrets, and load balancing.
• Test-forward approach with unit/integration/contract tests.
• Knowledge of API security (OAuth/JWT) and tenancy isolation.

Responsibilities

• Grow API surface with new endpoints, webhooks, and richer querying options for partners.
• Improve partner integration with OpenAPI specs, docs, and sandbox environments.
• Harden the platform with rate limiting, secret rotation, contract testing, and pen-test remediation.
• Build for scale with multi-partner onboarding, tenant isolation, load testing, and caching.
• Establish SLOs, alerts, and strong observability patterns.

Skills

TypeScript

Node.js

REST API design

OpenAPI

AWS

Tools

OpenAPI

AWS

Job description

Backend Engineer API Development | Fintech Scale-up Backed by a Major Bank | AWS & TypeScript

A fast-growing fintech scale-up in the business financing space, backed by a major bank, is looking for an independent backend engineer to help build, harden and scale its secure API platform. The internal lending logic is already covered by the in-house team, so this role is pure backend and API craft: growing the partner-facing surface, tightening security, and getting the platform ready to onboard more partners at scale.

It is a deliberately simple, well-structured codebase, held to the standards you would expect from a financial institution. You will work with a modern TypeScript and Node.js stack on AWS, and the project leans heavily on agentic, AI-assisted development, so someone who can direct and review that kind of output well will genuinely multiply the team’s output rather than just add a pair of hands.

About the role

You will take ownership of the partner-facing API platform end to end, from spec and design through to tested, production-ready delivery. Rather than executing a backlog of tickets, you will help break down the work, sequence it, and drive it to a clear done, working closely with a small, senior team.

• Grow the API surface cleanly: new endpoints, webhooks and callbacks, and richer querying options for partners.
• Improve the developer experience for partners integrating with the platform: clear contracts, published OpenAPI specs, integration docs and sandbox environments.
• Harden the platform: rate limiting, secret rotation, contract testing and remediation of pen-test findings.
• Build for scale: repeatable multi-partner onboarding, tenant isolation, load and performance testing, and caching.
• Raise platform quality: SLOs, alerting and resilience patterns, backed by strong observability.

Who are you?

• Strong hands-on backend development experience in TypeScript and Node.js, building server-side HTTP services with clean, typed code.
• Solid REST/JSON API design skills: versioning, consistent error contracts, idempotency, pagination and an API-as-contract mindset using OpenAPI.
• Mandatory hands-on AWS experience with core services such as containers or compute, queuing, managed databases, secrets and load balancing.
• A test-forward mindset, comfortable driving work through unit, integration and contract tests as part of building, not as an afterthought.
• Practical knowledge of API security: token-based auth (OAuth/JWT), authorization and tenancy isolation, and secure secret handling.