Principal Fullstack Engineer

We are looking for a Principal Full-Stack Engineer to take technical ownership across backend and frontend development, shaping high-quality, scalable solutions and setting engineering standards for the team. This role combines hands-on delivery with technical leadership, mentoring, and close collaboration with product and platform teams.

You will work across modern backend services built in Kotlin, rich frontend applications using React and Next.js with TypeScript, and cloud-native infrastructure on Azure or AWS.

This is an initial 6 month contract (outside iR35) that requires you onsite in London Paddington 3 days a week.

Key Responsibilities

• Lead the design and development of full-stack solutions, balancing backend robustness with high-quality user experiences
• Build and maintain backend services using Kotlin, following clean architecture and best practices
• Develop modern, performant frontends using React, Next.js, and TypeScript
• Take ownership of API design, integration, and lifecycle management using Apigee
• Design and operate cloud-native solutions using Azure or AWS, including containerised workloads
• Champion strong observability practices, ensuring systems are reliable, measurable, and easy to troubleshoot
• Set technical direction, standards, and best practices across the team
• Mentor and support other engineers through code reviews, pairing, and technical guidance
• Collaborate closely with Product, DevOps, and Architecture to deliver scalable, secure solutions

Requirements

Required Skills & Experience

• Proven experience in a Lead or Senior Full-Stack Engineering role
• Strong backend development experience with Kotlin
• Solid frontend expertise with React, Next.js, and TypeScript
• Experience building and operating cloud-based systems on Azure or AWS
• Hands-on experience with containerisation (e.g. Docker, Kubernetes or similar)
• Strong experience with API management, ideally using Apigee
• Deep understanding of observability, including logging, metrics, tracing, and alerting
• Experience designing and maintaining scalable, production-grade systems
• Strong communication skills and the ability to influence technical decisions

Nice to Have

• Experience working in complex, distributed systems
• Exposure to CI/CD pipelines and DevOps practices
• Experience modernising legacy systems or platforms

Benefits

We offer

• Competitive Rates
• Flexible working arrangements
• Opportunities for professional development and career advancement within a global company
• A dynamic, innovative, and supportive work environment, where your ideas and contributions are valued
• The chance to work on cutting-edge projects that are transforming the industry
• Most of all you get to work with a bunch of great people, where the whole team owns the project together in a politics-free environment. Our culture reflects our lean and self-organisation attitude. We encourage our colleagues to take risks, make decisions, work in a collaborative way and talk to everyone to enhance communication. Freedom and Responsibility go hand in hand, and we value commitment, feedback, and empathy.