Senior Software Engineer

Senior Software Engineer Legacy to Modern C#, .Net SaaS Data

A fast-growing SaaS business is investing heavily in its tech platform and building out a senior engineering hub in London. They're on the lookout for a Senior Software Engineer to help drive modernisation, set technical direction, and mentor squads as they scale.

This is a senior, hands-on role. You'll design and build applications, lead migrations away from legacy frameworks, and ensure the platform is stable, scalable, and fit for the future. Expect to spend plenty of time coding, alongside leading migrations and leading/mentoring 4 engineers.

You will have complete autonomy for all things C# .NET in the business, including decision making on strategy around the direction of the products, the projects, leading the team and liaising with external consultancies etc.

What you'll be doing:

• Design and build complex apps with C# and .NET Core/Framework
• Lead migrations from Web Forms/ASMX to modern stacks (.NET Core, MVC, REST APIs)
• Contribute to the technical roadmap and influence best practices across squads
• Partner with QA, Product, and DevOps to deliver reliable features in agile sprints
• Implement and fine-tune CI/CD (TeamCity, Octopus)
• Manage deployments across IIS and AWS
• Mentor developers through code reviews and guidance
• Optimise SQL/T-SQL performance for production systems

What we're looking for:

• Strong background in C# and modern .NET Core
• Comfortable balancing legacy upkeep with platform modernisation
• Confident with IIS, AWS, TeamCity, Octopus Deploy, SQL Server
• Bonus points for exposure to Angular or Telerik libraries
• Prior experience as a senior engineer in SaaS or product-led teams
• Someone who enjoys mentoring, influencing direction, and staying hands-on

Location & working style:

Hybrid London role, with 1-2 days a week in the office. Squads value autonomy, collaboration, and building things that last.

Senior Software Engineer Legacy to Modern C#, .Net SaaS Data