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

- **Company:** The Source
- **Location:** London, UK
- **Experience:** Expert
- **Contract:** Permanent contract
- **Skills:** Clean Code Principles, ASP.NET, HTML, .NET Framework, Application Programming Interfaces (APIs), Amazon Web Services, Audit Trail, Automation of Tests, Microsoft Azure, C Sharp (Programming Language), Relational Databases, Dependency Injection, Entity Framework, Design of User Interfaces, Microsoft SQL Server, OAuth, OpenID, RabbitMQ, Secure Coding, SQL Databases, TypeScript, Data Logging, .NET Core, ReactJS, Backend, Event Driven Architecture, Containerization, Solid Principles, Low Latency, Bicep, Apache Kafka, Asynchronous Programming, Restful APIs, Terraform, Docker, Microservices
- **Published:** October 22, 2026
- **Apply:** https://www.apply4u.co.uk/jobs/senior-full-stack-developer-cnet-react-london/52867078

## About the Role

end-to-end) and participate in code reviews.Collaborate with product, design, and stakeholders to refine requirements and deliver to CI/CD pipelines and cloud deployment practices.Mentor engineers and promote best practice in engineering craft and delivery.Required Skills & ExperienceExtensive 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.DesirableExperience 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 BringOwnership mindset, pragmatic decision-making, and a focus on delivering value safely.Commitment to engineering excellence, continuous learning, and improving team ways of working.

## Description

Reference: 57984Location: London, United KingdomIndustry: Financial ServicesSalary: 160,000OverviewWe 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 ResponsibilitiesDesign, 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