Senior Full Stack Engineer (.NET/Vue)

Our client is an established and growing SaaS company providing specialised software solutions to a non-technology service industry. Its platform helps customers streamline operations, improve customer experiences, and modernise traditional business processes.

The engineering team places a strong emphasis on quality, maintainability, automation, and engineering discipline. AI-assisted development is actively encouraged to accelerate delivery, but all AI-generated code is subject to the same standards of security, testing, verification, and production readiness as traditionally developed software.

We are looking for a Senior Software Engineer to play a key role in the ongoing modernisation of a long-standing, business-critical platform.

You will work across both legacy and modern technology stacks, helping evolve an application built with Classic ASP, .NET Framework, SQL Server, modern .NET, and Vue 3.

This is an ideal role for an engineer who enjoys solving complex technical problems, understands the realities of legacy systems, and can make pragmatic improvements without over-engineering.

You will contribute to both maintaining the existing platform and delivering new capabilities using modern technologies, while helping reduce technical debt, improve test coverage, and strengthen overall engineering practices.

• → Develop clean, reliable, secure, and maintainable software across both legacy and modern platforms.
• → Work extensively with Classic ASP and .NET Framework 4.x, including existing Windows Services and IIS-hosted applications.
• → Build new services, APIs, and features using modern .NET / ASP.NET Core, including .NET 8/9.
• → Contribute to frontend modernisation using Vue 3.
• → Incrementally refactor and modernise legacy components while maintaining system stability and customer workflows.
• → Work with complex Microsoft SQL Server environments, including stored procedures, views, indexes, complex queries, and performance optimisation.
• → Use both Entity Framework and direct SQL where appropriate.
• → Improve automated testing, particularly unit test coverage, and work effectively with QA across different levels of testing.
• → Use AI coding assistants and agents as part of the development workflow while ensuring generated code is properly reviewed, tested, and verified.
• → Help develop reusable AI-assisted engineering workflows and verification practices.
• → Collaborate with product, engineering, QA, and other stakeholders to clarify requirements and acceptance criteria.
• → Make pragmatic technical decisions that balance business priorities, delivery speed, maintainability, and long-term platform stability.
• → Contribute to improvements in development, testing, deployment, and engineering processes.

You are a pragmatic senior engineer who is comfortable working in complex and evolving environments. You understand that modernisation is often an incremental process and can balance the need to improve a system with the need to keep it running reliably.

• 5+ years of professional software engineering experience.
• Strong hands-on experience with .NET Framework 4.x and C#.
• Solid experience working with Classic ASP and legacy application environments.
• Experience with Windows Services and IIS-hosted applications.
• Strong experience with Microsoft SQL Server, including:
  • Complex queries
  • Stored procedures
  • Views
  • Indexing
  • Query and database performance tuning
• Experience developing with modern .NET / ASP.NET Core Web APIs.
• Frontend development experience with Vue.js, preferably Vue 3.
• Experience with automated testing, including unit testing and E2E testing.
• Experience working across both backend and frontend development.
• Strong understanding of software quality, maintainability, security, and technical debt.
• Fluent written and spoken English.

• Experience with .NET 8/9.
• Experience with Docker.
• Exposure to AWS.
• Experience modernising or migrating legacy applications.
• Experience working with AI coding assistants, coding agents, or AI-assisted development workflows.
• Experience creating automated verification or quality-control processes for AI-generated code.

• Pragmatic engineering: You focus on solving the right problem rather than over-engineering solutions.
• Legacy expertise: You are comfortable understanding and improving systems that may have been around for many years.
• Modernisation mindset: You know when to refactor, when to replace, and when to leave something alone.
• Quality ownership: You take responsibility for the quality of what you build and understand the value of testing at different levels.
• AI fluency: You see AI as an engineering accelerator, not a replacement for engineering judgement.
• Strong collaboration: You communicate clearly with technical and non-technical stakeholders and work effectively within distributed teams.
• Continuous improvement: You actively look for ways to improve code, processes, tooling, and engineering practices.