Key Skills

Job Description

Introduction 36 hours per week Start: asap End: 01 June 2027 Possible extension: Yes ZZP is allowed Hybrid way of work Candidates MUST live in the Netherlands at this moment Backend Engineer - API Development The role in one line: An independent backend engineer to help build, harden, and scale our secure APIs - strong on API craft, security, and testing, and able to help drive delivery, not just execute tickets. Context: Work across our API surface, held to real financial-institution standards for security, reliability, and testing. It's a deliberately simple, well-structured codebase. No internal/domain business knowledge required, that's owned in-house. We need backend and API strength. Where they add the most value: Since internal logic is covered, their leverage is on the partner-facing platform and developer experience: - Growing the API surface cleanly (new endpoints, webhooks/callbacks, richer querying) - Developer experience - clear contracts, published API specs, integration docs, sandbox environments - Hardening - rate limiting, secret rotation, contract testing, pen-test remediation - Scaling - repeatable multi-partner onboarding, tenant isolation, load/performance testing, caching - Platform quality - SLOs, alerting, resilience patterns Ways of working: - Independent and self-directing - takes a capability from spec → design → tested delivery without hand-holding - Helps manage the work - can break down a body of work, sequence it, and drive it to a clear "done" - Spec- and documentation-driven - at home working from and writing specs, acceptance criteria, and decision records; a clear, concise writer - Comfortable with AI-assisted / agentic development - this project is built heavily with agentic tooling; someone who can direct and review that output well is a real multiplier - Quality-first and pragmatic - treats security, testing, and observability as ship-blocking, while favoring simple solutions over over-engineering Requirements Core skills: - Modern backend development in TypeScript / Node.js - server-side HTTP services, networking fundamentals, clean typed code - REST/JSON API design - versioning, consistent error contracts, idempotency, pagination, and an API-as-contract mindset (OpenAPI) - Relational data - schema design, migrations, and a data-integrity mindset - Asynchronous & queue-driven systems - background workers, job lifecycles, retries, idempotent processing - API security - token-based auth (OAuth/JWT), authorization and tenancy isolation, secure secret handling, "fail-closed" defaults, and awareness of industry baselines (e.g. OWASP API Security Top 10) - Test-forward development - comfortable driving work through unit, integration, and contract tests as a first-class part of building, not an afterthought - Hands-on AWS experience (mandatory) - must know the specifics of core AWS services (containers/compute, queuing, managed databases, secrets, load balancing). Given the short timeline and MVP nature, we prefer they not need to onboard onto a new cloud; - Cloud-native delivery - building and shipping containerized services, infrastructure-as-code (Terraform ideal), CI/CD pipelines - Observability - structured logging, metrics, tracing, and audit trails; can debug production from telemetry Nice-to-haves: fintech or other regulated-domain experience · platform / API-gateway team background · leading a small delivery independently.

Core Responsibilities

Build, secure, and scale partner-facing APIs, including endpoints, webhooks, API specifications, and integration documentation. Improve platform reliability and quality through security hardening, multi-partner onboarding, performance testing, observability, and independently driven delivery.

Requirements

Requires strong backend development experience with TypeScript and Node.js, REST/JSON API design, relational data, asynchronous systems, API security, and test-forward development. Hands-on AWS experience is mandatory, along with cloud-native delivery and the ability to build, test, and ship services independently.