Principal Software Engineer

We are looking for a hands-on Software Architect to take ownership of a mission-critical legacy platform built on .NET Framework and SQL Server, while also leading the evolution of this system into a modern, scalable SaaS solution using microservices architecture and cloud-native technologies.

This role is a dual-focus opportunity — maintaining and enhancing existing systems while architecting and guiding the strategic transformation toward a modern platform using .NET 8, Vue.js, Azure, and Microservices.

• Serve as the technical owner and architect for a legacy enterprise application built using:
• .NET Framework 4.8 / .NET 8
• Angular 17
• SQL Server
• Azure Cloud
• IdentityServer4
• Lead the modernization roadmap, re-architecting the system to a SaaS model using:
• Vue.js frontend
• .NET 8 microservices
• Event-driven architecture / APIs
• Containerization (Docker/Kubernetes)
• CI/CD pipelines in Azure DevOps
• Ensure secure, scalable, and resilient application design patterns using modern DevOps and Cloud-native best practices.
• Collaborate with cross-functional teams including product managers, DevOps, and developers to align technical decisions with business goals.
• Perform code and architecture reviews, and provide mentorship to development teams.
• Maintain documentation of system architecture, integration patterns, and design decisions.
• Identify and mitigate technical risks in both legacy and modernized environments.
• Work in an Agile/Scrum environment to deliver features iteratively.

• 12+ years of experience in software engineering with minimum 3+ years in architecture roles.
• Deep understanding and hands-on experience with:
• .NET Framework and .NET Core/.NET 8
• Angular (preferably v17+)
• SQL Server and relational database design
• Azure PaaS (App Services, Azure SQL, Azure Functions, Key Vault, etc.)
• Proven track record of designing and implementing microservices architectures.
• Hands-on experience with Vue.js or willingness to adopt as the future front-end framework.
• Experience with Docker, Kubernetes, and CI/CD pipelines.
• Excellent knowledge of software design principles, design patterns, and best practices.
• Strong communication and stakeholder management skills.

• Wellbeing focused – Our people are our greatest assets, and ensuring everyone feels their best self to come to work is integral. 
• Annual Leave – 20 days of annual leave, plus public holidays 
• Employee Assistance Programme – Free advice, support, and confidential counselling available 24/7.
• Personal Growth - Regardless of where you are at in your career, we’re committed to enabling your growth personally and professionally
  • Development Programmes – From Future Managers to Leadership Training, our development programmes help you get where you need to go
  • Online Learning Platform: SkillsHub! - Learning at your fingertips, anytime from anywhere. You can access our online library with relevant content for your career growth. 
• Life Insurance - 3x annual salary 
• Personal Accident Insurance - providing cover in the event of serious injury/illness.
• Performance Bonus – Our Group-wide bonus scheme enables you to reap the rewards of your success

OneAdvanced is one of the UK's largest providers of business software and services serving 20,000+ global customers with an annual turnover of £330M+. We manage 1.5 million 111 calls per month, support over 2 million Further Education learners across the UK, handle over 10 million wills, and so much more. Our mission is to power the world of work and, as you can see, our software underpins some of the UK's most critical sectors.

We invest in our brilliant people. They are at the heart of our success as we strive to be a diverse, inclusive and engaging place to work that not only powers the world of work, but empowers the growth, ambitions and talent of our people.

To learn more about working at OneAdvanced please click here