Senior .NET Developer

Senior .NET Developer – Hybrid – Up to £850/day Inside IR35 | C# | On-Prem | Event-Driven Systems | Kafka | Energy Trading We have a unique opportunity for a Senior .NET Developer to join a leading energy trading business. As the Senior .NET/Full Stack Developer, you’ll play a key role in shaping and scaling a high-performance energy trading platform as the business enters its next phase of growth. This includes developing new trading capabilities, integrating with energy markets and external data providers, and expanding a platform that supports critical trading, pricing, and risk processes. You’ll be working on a high-performance, on-premise technology platform built with .NET and C#, designed around API-driven architecture, event-driven services, and distributed systems. The platform supports real-time market data, trading workflows, pricing, position management, and high-volume financial and energy transactions. This is a hands-on technical leadership role where you’ll help drive engineering best practices, contribute to architectural decisions, and mentor developers while remaining close to the code. Working closely with Traders, Quantitative Analysts, Risk, Data, and Platform teams, you’ll help evolve the platform architecture and deliver secure, scalable, resilient, and high-performance distributed systems within a fast-moving energy trading environment. 📍 2 days per week in the office – City of London 💰 Up to £850/day Inside IR35 🗓️ Initial 6-month contract Responsibilities Lead the design and development of high-performance .NET services supporting an energy trading platformBuild and scale event-driven services and distributed systems within an on-premise environmentDevelop systems supporting trading, pricing, market data, positions, and risk workflowsWork with real-time and high-volume energy market data and trading eventsDrive best practices across architecture, coding standards, observability, performance, and reliabilityWork closely with Traders, Risk, Data, and Product teams to translate trading requirements into robust technical solutionsDesign and develop API-driven integrations with internal systems, market data providers, and external trading platformsDevelop and maintain high-throughput, low-latency services where performance and reliability are criticalMentor and support engineers across the team while contributing hands-on to critical systemsHelp evolve a scalable, distributed on-premise architecture capable of handling high-volume, time-sensitive workloadsContribute to improving engineering velocity, delivery quality, platform resilience, and operational performance What we’re looking for Strong experience building production systems with .NET / C#Strong experience working with on-premise enterprise environmentsStrong experience with event-driven architectures such as Kafka and other messaging platformsExperience with distributed databases / NoSQL technologies, including Cosmos DB or equivalentProven experience building distributed systems and scalable APIsExperience working within energy trading, commodities trading, financial markets, or other high-performance trading environmentsUnderstanding of market data, trading workflows, pricing, positions, or risk systemsStrong understanding of system design, reliability, concurrency, and performance at scaleExperience designing systems where low latency, throughput, resilience, and data accuracy are criticalExperience working with Windows Server, IIS, networking, and on-premise infrastructure would be advantageousAbility to lead technically while remaining hands-on in development Senior .NET Developer – Energy Trading – Hybrid – £850/day Inside IR35 | C# | On-Prem | Kafka | Event-Driven Systems | Trading | Market Data