Senior Software Engineer

Harrington Starr; United States; Remote; GBP 120,000 - 160,000; Full time

Benefits offered by this job

Fully remote UK-wide

Flexible working

Learning & career development

Private healthcare

Enhanced holiday allowance

Share option potential

Shape cutting-edge AI products

Job summary

Harrington Starr partners with an innovative fintech AI specialist to hire a Senior AI Software Engineer. You will own AI feature delivery from concept to production, designing platforms, services, and user interfaces that integrate LLMs and agentic workflows.

Lead backend and frontend work using Node.js/TypeScript and React, with a strong cloud-native focus on AWS. Mentoring engineers and driving observability and best practices are key parts of the role.

Qualifications

• Experience building AI-enabled production systems for financial services is a plus.
• Strong backend with Node.js/TypeScript and React experience.
• Proven ability to ship end-to-end AI-powered features in production.

Responsibilities

• Build AI-powered products using LLMs, RAG, and agentic workflows in production.
• Develop backend services and APIs with Node.js/TypeScript and NestJS.
• Create modern React UIs that embed AI into user workflows.
• Lead design of cloud-native solutions on AWS and monitor AI systems.

Skills

Node.js

TypeScript

React

AWS

Microservices

API design

NLP/LLMs

Prompt engineering

Team mentorship

Observability

NestJS

LangGraph

Langfuse

Tools

NestJS

LangGraph

Langfuse

AWS

Job description

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.

What You'll Be Doing

• 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 TypeScript.
• 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, TypeScript, 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 LangGraph, 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.

What's On Offer

• 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