Referment is working with a consumer fintech platform offering lending and payment experiences to people seeking short-term finance. It is looking for a Senior Full-Stack Engineer to build and operate production software using AI coding agents, while retaining personal responsibility for the architecture and quality of what ships.

This is a hands-on engineering role, not a people-management position. You'll direct agents across frontend, backend and infrastructure work, turning product requirements into executable tasks and reviewing the results before they reach customers. Knowing when to intervene or write the code yourself is as important as knowing how to delegate work to an agent.

You'll work with Product and Design on delivery, and own the controls that make agent-assisted development dependable: tests, evaluation harnesses, code review, deployment gates and production monitoring. The opportunity is to shape the development workflow as well as the applications it produces.

The Role

• Deliver full-stack features across consumer financial products, taking responsibility for interfaces, APIs, services and data layers.
• Orchestrate AI agents from specification through pull requests and deployment, verifying and integrating their output.
• Design workflows, prompts, guardrails and evaluation standards for production coding, testing and review.
• Build CI checks and review gates that keep generated code secure, correct and auditable.
• Make architecture decisions and maintain application performance, reliability and security end to end.
• Monitor system health and incidents, bringing human judgement to situations agents cannot safely resolve.
  
  

What We're Looking For

• At least six years of full-stack engineering experience delivering production systems.
• Strong frontend skills in React or a similar framework, alongside backend APIs and services, databases and cloud infrastructure.
• Hands-on experience directing AI coding agents or LLM-based workflows in production, beyond experimentation.
• Sound testing, code review, security and deployment practices, with evidence of systems you've shipped and can explain in depth.
• The judgement to operate independently, check agent output critically and take ownership of production outcomes.
  
  

Useful Background

Fintech, lending or payments experience is useful, as are mobile development skills in React Native or native iOS/Android. Experience building CI/CD, observability or evaluation systems for agent pipelines would also be relevant.

This could suit a senior or staff-level product engineer who already uses agents in production and wants to combine broad technical ownership with disciplined, hands-on delivery.

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