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

Location: London, United Kingdom

Industry: Financial Services

Salary: £160,000

Overview

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.