Backend Engineer (TypeScript/Nodejs)
Summary
Backend Engineer owning a partner-facing API platform for a fintech lending scale-up, using TypeScript, Node.js, and AWS with a focus on security, scalability, and AI-assisted development.
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.