Senior C# .Net Developer

Arm; City Of London; Hybrid; GBP 80,000 - 105,000; Part time

Job summary

Arm in London is seeking an experienced Senior C# .NET Developer to join a strategic technology transformation programme on a contract basis. The role focuses on designing, developing and enhancing enterprise-grade applications across front-, middle-, and back-office domains within a regulated banking environment.

You will work with Solution Architects, Tech Analysts, BAs, Data Engineers and QA to deliver scalable, secure solutions.

Qualifications

• Strong commercial C#/.NET development experience.
• Experience with .NET Core / .NET 6+ and ASP.NET Core/Web API.
• Proficient with REST APIs and microservices architectures.
• SQL Server expertise including complex queries & stored procedures.
• Experience with ORM tools (Entity Framework) and design patterns.
• Proficient in unit/integration testing and test automation.
• Exposure to Azure DevOps, Git and CI/CD pipelines.
• Agile/Scrum delivery mindset and stakeholder collaboration.

Responsibilities

• Design, develop and maintain enterprise applications using C# and .NET.
• Build scalable APIs and distributed services with security in mind.
• Translate business requirements into technical solutions with stakeholders.
• Contribute to solution architecture, design decisions and code reviews.
• Develop RESTful APIs and integration services.
• Implement monitoring, logging and error handling.
• Work with SQL Server and other databases; optimise queries.
• Write automated unit, integration and regression tests.
• Support CI/CD and DevOps practices in the team.
• Troubleshoot production issues and perform root-cause analysis.
• Adhere to engineering, security and development standards.
• Participate in Agile delivery and cloud adoption initiatives.

Skills

C#/.NET development

.NET Core/.NET 6+

ASP.NET Core/Web API

REST APIs/microservices

SQL Server/SQL

Entity Framework/ORM

OO design & patterns

Unit/integration testing

Azure DevOps

Git/CI-CD

Agile/Scrum

Troubleshooting

Tools

Azure DevOps

Git

Docker

Kubernetes

Kafka

RabbitMQ

Azure Service Bus

Redis

Swagger/OpenAPI

Job description

Role: Senior C# .NET Developer

Location: London, UK

Working Pattern: Hybrid, 3 days per week onsite, Canary Wharf or Liverpool Street

Employment Type: Contract

Rate: £500 a day Inside IR35 via Umbrella

Role Overview

We are seeking experienced Senior C# .NET Developers to join a strategic technology transformation programme within a leading international banking environment.

The successful candidates will design, develop and enhance enterprise-grade applications supporting critical business functions across front-office, middle-office and back-office domains. They will work closely with Solution Architects, Technical Analysts, Business Analysts, Data Engineers and QA teams to deliver scalable, secure and high-performing solutions in a highly regulated environment.

Key Responsibilities

• Design, develop and maintain enterprise applications using C# and .NET.
• Develop scalable, secure and high-performance APIs, services and distributed applications.
• Work with Technical Analysts and business stakeholders to translate requirements into technical solutions.
• Contribute to solution architecture, technical design and code reviews.
• Develop RESTful APIs and integration services.
• Implement monitoring, logging and error handling.
• Work with relational and non-relational databases.
• Develop automated unit, integration and regression tests.
• Support CI/CD and DevOps practices.
• Troubleshoot production issues and perform root-cause analysis.
• Follow engineering, security and development standards.
• Participate in Agile delivery.
• Support application modernisation and cloud adoption.

Mandatory Skills

• Strong commercial C#/.NET development experience
• .NET Core / .NET 6+
• ASP.NET Core / Web API
• REST APIs and microservices
• SQL Server, including complex queries, stored procedures and optimisation
• Entity Framework / ORM
• Object-oriented design and design patterns
• Distributed systems and enterprise integration
• Unit and automated testing
• Azure DevOps, Git and CI/CD
• Agile/Scrum delivery
• Strong troubleshooting and problem-solving capability
• Good stakeholder communication

Desirable

• Banking, Capital Markets or Financial Services
• Azure
• Docker / Kubernetes
• Kafka, RabbitMQ or Azure Service Bus
• Event-driven architectures
• React / Angular
• Cloud-native development
• Application observability and performance engineering
• DevSecOps and secure coding

Preferred Stack

C# | .NET Core/.NET 8 | ASP.NET Core | REST APIs | SQL Server | Entity Framework | Azure | Azure DevOps | Git | Docker | Kubernetes | Kafka | Redis | JSON/XML | Swagger/OpenAPI