Senior .Net Developer

Salary: £65,000 - 65,000 per year

Requirements:

• Strong .NET development experience working on complex or business-critical systems
• Experience in billing/invoicing systems or transactional financial products
• Ability to take ownership of an existing system and understand legacy code
• Strong C# / .NET and SQL Server experience
• Experience with APIs and system integrations
• Ability to troubleshoot issues and explain system behaviour to non-technical stakeholders
• Exposure to containerisation, such as Docker
• Familiarity with modern DevOps practices
• Experience with reverse engineering, transformation programmes, or modernisation initiatives
• Experience working in environments with limited documentation
• Experience using AI-assisted engineering tools such as Claude or Copilot in production

Responsibilities:

• Work within a complex billing environment supporting system stabilisation, reverse engineering and transformation
• Analyse existing code to uncover undocumented behaviours
• Translate technical findings into clear documentation for technical and business teams
• Work closely with Billing SMEs, Business Analysts and programme stakeholders
• Act as the bridge between technical implementation and real-world billing processes
• Support ongoing changes and enhancements to the existing billing platform
• Ensure delivered work aligns with the transition to a new enterprise billing system
• Use AI-assisted tooling to improve understanding, documentation and delivery

Technologies:

• AI
• C#
• Copilot
• DevOps
• Docker
• Support
• SQL
• ASP.NET
• API
• Cloud
• Security

More:

We are a globally connected business operating at the heart of international trade, with a worldwide name and over 100,000 employees following recent acquisitions. You will join us on a 2-year fixed-term contract within a major multi-year Billing Transformation Programme, where we are replacing a complex legacy billing platform with a modern enterprise solution. This is a high-impact, well-invested programme with the opportunity to introduce AI into production. The role is hybrid, with a minimum of 3 days per week in our Southampton office. We offer a 10% bonus, 8% pension, private medical cover, life assurance, and 25 days holiday plus bank holidays. This role cannot offer visa sponsorship.

last updated 32 week of 2026