Senior Fullstack Engineer

About the Role

We 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 Details

Our 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

• Design, 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.

Qualifications

Preferred Qualifications

• Strong 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.