Senior Fullstack Engineer

ClientN BrownBriefWe are looking for a highly experienced, AI-native Senior Fullstack Engineer to take ownership of building, improving, and scaling production-grade software solutions.This role is suited to an engineer who has fully embraced AI-driven software development and uses AI coding agents as a fundamental part of their engineering workflow. We are not looking for a traditional developer who occasionally uses AI tools. We need someone who knows how to leverage AI to design, build, test, debug, and ship high-quality production software at pace.You will work primarily with Node.js and AWS, developing and integrating solutions across commercial platforms, payments, fraud, originations, and financial infrastructure.The ideal candidate is a proactive, hands-on engineer who can operate independently, make sound technical decisions, solve complex problems, and drive delivery from initial requirements through to production with minimal supervision.Company DetailsOur client is a well-established UK-based digital retail and financial services organisation with a strong focus on technology, customer experience, and innovation.The business operates across retail, payments, credit, fraud, and financial services, with a growing investment in modern cloud technology and AI-driven software development.This is an opportunity to join a business undergoing technology transformation, working with modern platforms, APIs, AWS, Node.js, and AI development tools such as Claude Code and Cursor. Responsibilities and AttributionsResponsibilitiesDesign, develop, and maintain production-grade applications and backend services using Node.js, JavaScript, and TypeScript.Build scalable, secure, and reliable backend systems and APIs using Node.js.Use AI coding agents such as Claude Code, Cursor, or similar tools as core development tools, not simply as occasional assistants.Leverage AI agents to accelerate development, refactoring, debugging, testing, documentation, and code generation while maintaining full ownership of the resulting code.Translate business and product requirements into robust technical solutions and deliver them from development through to production.Build and integrate REST APIs, third-party platforms, and SaaS solutions.Develop integrations across payments, fraud, originations, and financial infrastructure.Work with AWS services to deploy, operate, monitor, and scale applications.Review and validate AI-generated Node.js code to ensure security, performance, maintainability, and reliability.Refactor and modernise existing applications and services where required.Implement automated testing, CI/CD pipelines, and appropriate engineering quality controls.Troubleshoot production issues and improve application performance, reliability, and observability.Take full ownership of technical delivery, proactively identify problems, and make sound engineering decisions without constant supervision.Collaborate with technical and business stakeholders while working independently and maintaining alignment with UK business hours. Requisites and QualificationsQualificationsPreferred QualificationsStrong hands-on experience with Node.js and proven experience building, developing, and maintaining production-grade backend applications and services.Strong proficiency in JavaScript and/or TypeScript.Practical experience designing, building, deploying, and maintaining applications on AWS.Strong backend engineering skills, including API development, system integration, and software architecture.Experience with databases, data modelling, automated testing, CI/CD, and Git.Significant commercial experience in a senior software engineering or equivalent hands-on development role.Ability to review, validate, debug, and secure code, including AI-generated code, while maintaining high standards of engineering quality.Proven ability to work independently, take ownership of delivery, and solve complex technical problems with minimal supervision.A proactive mindset, strong problem-solving skills, and the confidence to make technical decisions without hand-holding.Strong written and verbal English communication skills.Ability to work UK business hours.AI-native development experience: Uses AI coding agents as a fundamental part of the development workflow, rather than relying on AI tools only occasionally.Hands-on experience with Claude Code, Cursor, GitHub Copilot, or similar AI-powered development tools.Experience using AI agents throughout the software development lifecycle, including planning, implementation, debugging, refactoring, testing, and production delivery.Experience in fintech, financial services, payments, fraud, credit, or other regulated commercial environments.Experience integrating third-party SaaS platforms and external APIs.Experience with cloud-native architectures, distributed systems, and production operations.