Senior .Net Developer (Billing Systems Essential)

Salary: £60,000 - 65,000 per year

Requirements:

• We require strong .NET development experience on complex or business-critical systems within billing/invoicing or transactional financial products.
• We require experience working on systems tailored to different customer needs.
• We require the ability to take ownership of an existing system, including reading and understanding legacy code.
• We require strong troubleshooting skills and the ability to explain system behaviour to non-technical stakeholders.
• We require solid experience with C# / .NET, SQL Server and APIs.
• We require an understanding of system integration and handling complex data.
• We require exposure to containerisation, such as Docker, and modern DevOps practices.
• We require that you can work in the UK without visa sponsorship.

Responsibilities:

• We work on a complex billing environment, supporting system stabilisation, reverse engineering and transformation activities.
• We analyse existing code and uncover undocumented behaviours.
• We translate technical findings into clear documentation and understanding for technical and business teams.
• We collaborate closely with Billing SMEs, Business Analysts and programme stakeholders.
• We act as a bridge between technical implementation and real-world billing processes.
• We support ongoing changes and enhancements while aligning delivery to the longer-term billing system transition.
• We use modern engineering practices, including AI-assisted tooling, to improve understanding, documentation and delivery.

Technologies:

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

More:

We are a globally connected business operating at the heart of international trade, with a worldwide reputation and over 100,000 employees following recent acquisitions. We are delivering a major multi-year billing transformation programme, replacing a complex legacy billing platform with a modern enterprise solution, with strong investment in modernisation and the opportunity to introduce AI in production. This is a 2-year fixed term contract based in Southampton with a hybrid working model requiring a minimum of 3 days per week in the office. We offer a competitive package including a £60,000-£65,000 salary, 10% bonus, 8% pension, private medical cover, life assurance and 25 days holiday plus bank holidays. This role suits someone who wants the security of a multinational environment with the collaboration of an SME.

last updated 32 week of 2026