Senior Full Stack Developer | C#.NET, React | London

Location: London, United KingdomIndustry: Financial ServicesSalary: 160,000Overview We are seeking a Senior Full Stack Developer to build and enhance high-performance, secure digital products within Financial Services. You will work across backend services and modern web front ends, contributing to architecture, delivery, and continuous improvement. This is a hands-on role with strong influence over engineering standards, quality, and technical direction.Key Responsibilities Design, develop, test, and maintain scalable services using C#/.NET (ASP.NET Core) and RESTful APIs.Build responsive, accessible user interfaces using React, TypeScript, HTML, and CSS.Implement secure authentication/authorisation (e.g., OAuth2/OIDC) and follow secure coding practices.Optimise performance, reliability, and observability (logging, metrics, tracing).Work with relational databases (e.g., SQL Server) including schema design, queries, and tuning.Write automated tests (unit, integration, end-to-end) and participate in code reviews.Collaborate with product, design, and stakeholders to refine requirements and deliver iteratively.Contribute to CI/CD pipelines and cloud deployment practices.Mentor engineers and promote best practice in engineering craft and delivery.Required Skills & Experience Extensive commercial experience in full stack development with C#/.NET and React.Strong knowledge of .NET Core, dependency injection, asynchronous programming, and API design.Strong React experience including state management and modern front-end tooling.Solid understanding of software design principles, patterns, and clean code practices.Experience with SQL databases, ORM tooling (e.g., Entity Framework), and data modelling.Experience with cloud platforms (Azure and/or AWS), containerisation (Docker), and CI/CD.Understanding of Financial Services constraints: security, auditability, data protection, and resiliency.Strong communication skills and ability to work effectively in an agile environment.Desirable Experience with microservices, event-driven architecture (e.g., Kafka/RabbitMQ), and distributed systems.Infrastructure as Code (e.g., Terraform/Bicep) and advanced monitoring/alerting practices.Experience building systems with low latency and high throughput requirements.What You’ll Bring Ownership mindset, pragmatic decision-making, and a focus on delivering value safely.Commitment to engineering excellence, continuous learning, and improving team ways of working.