Senior Software Engineer

Harrington Starr has partnered with an innovative technology company at the forefront of AI adoption within financial services. Having built a suite of production-grade AI products used by regulated financial organisations, they're now looking to hire a Senior AI Software Engineer to help scale the next generation of intelligent, customer-facing applications.

This is a hands-on engineering role where you'll own the delivery of AI-powered features from concept to production. Rather than building foundation models, you'll focus on designing and developing the platforms, services, integrations, and user experiences that bring large language models and agentic workflows into real-world business environments.

• Building AI-powered products that leverage LLMs, RAG architectures, and agentic workflows in production environments.
• Designing and developing backend services and APIs using Node.js and Type Script.
• Creating modern React-based user interfaces that embed AI into customer workflows.
• Architecting cloud-native solutions across AWS
• Implementing observability, monitoring, evaluation frameworks, and operational controls for AI systems.
• Working closely with product and engineering teams to deliver reliable, scalable, customer-facing solutions.
• Mentoring engineers and contributing to technical leadership across the team.
• Strong commercial experience building and operating production AI/LLM applications.
• Deep expertise with Node.js, Type Script, and React.
• Experience with prompt engineering, RAG, AI orchestration, and agentic systems.
• Strong AWS and cloud-native engineering background.
• Experience designing microservices, distributed systems, and event-driven architectures.
• Passion for clean code, testing, automation, and engineering best practices.
• Experience with NestJS.
• Knowledge of Lang Graph, Langfuse, or similar AI tooling.
• Experience delivering AI solutions within regulated environments such as financial services, banking, insurance, or fintech.
• Expertise in AI evaluation frameworks and production observability.

• Fully remote UK-wide working
• Flexible working environment
• Strong focus on learning and career development
• Private healthcare and comprehensive benefits package
• Enhanced holiday allowance
• Share option potential
• Opportunity to shape cutting-edge AI products used in highly regulated industries