Senior C# .NET Developer

Senior C# .NET Developer (Contract)

Location: London (1 day per week in office)
Rate: £475 per day
Engagement: Outside IR35

A well-established and highly specialised organisation operating within the infrastructure and environmental services sector is seeking an experienced Senior C# .NET Developer to join their team on a contract basis. This role will focus on enhancing and maintaining a suite of critical internal systems that support core business operations.

You will be working as a senior product engineer within a fast-paced, delivery-focused environment, contributing to the ongoing development of a business-critical platform. A key area of responsibility will be the integration layer, where you will design, build, and optimise APIs that enable seamless communication between internal and external systems.

This position requires a proactive, solution-oriented developer who is comfortable taking ownership of technical challenges and delivering high-quality solutions with minimal supervision. You will play an instrumental role in improving system scalability, performance, and reliability.

• Design, develop, and maintain robust backend services using C#, .NET, and .NET Core
• Build and enhance RESTful APIs and integration services to support data exchange across multiple platforms
• Work extensively with SQL Server, including writing and optimising stored procedures
• Collaborate with cross-functional teams (including product, QA, and operations) within an Agile/Scrum environment
• Participate in sprint planning, stand-ups, and retrospectives to deliver increments of high-quality software
• Troubleshoot and resolve complex technical issues, ensuring system stability and performance
• Contribute to architectural decisions and best practices across the development lifecycle

• Strong experience with C# and the .NET ecosystem (including .NET Core / .NET
  6)
• Proven track record of building and consuming APIs and integration services
• Solid understanding of relational databases, particularly Microsoft SQL Server
• Experience working with stored procedures, query optimisation, and data modelling
• Ability to work independently take on problems and quickly build and deliver solutions
• Being solutions orientated is a must
• Excellent communication skills