Summary
✨ AI‑Generated
A senior backend engineering contract focused on building, securing, testing, and scaling partner-facing APIs. You will expand API capabilities, improve developer experience through clear contracts and documentation, work with cloud infrastructure, and help drive reliable delivery under demanding security and testing standards.
Highlights
Independent backend engineering role focused on secure, reliable APIs, strong engineering standards, developer experience, clean architecture, and meaningful ownership of delivery in a hybrid environment.
Description
Introduction
36 hours per weekStart: 07 September 2026End: 01 June 2027Possible extension: YesZZP is allowedHybrid way of workCandidates MUST live in the Netherlands at this moment
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.
