Software Engineer jobs in Oxford

Gekko Group is looking for an experienced Senior Full Stack Developer to help modernise our in-house software platforms and consolidate our legacy systems into a single, cloud-based application.

This is a hands-on full-stack role covering the complete technology stack, from database and backend development through to the Angular user interface. You will be the sole developer for the migration of existing SQL Server databases and legacy ASP.NET applications to a modern architecture built around a cloud-hosted MySQL database, .NET Core APIs and a single Angular web application.

Working closely with our Lead Architect, you will analyse existing systems and business processes, plan and deliver migrations, and ensure that established functionality is transferred accurately into the new platform. This requires someone who can work confidently across the full stack, understand complex legacy systems and make sound technical decisions while maintaining business continuity.

This is an opportunity to play a key role in a significant modernisation programme, helping create a more consistent, maintainable and scalable foundation for Gekko's future software development.

We are an award-winning field marketing agency connecting leading leisure, lifestyle and technology brands with consumers across retail, online and B2B channels. Our in-house software platforms play an important role in supporting our operations, reporting and delivery of services to our clients.

If you enjoy solving complex technical challenges, modernising legacy applications and building robust full-stack solutions, we think this could be a great opportunity to join our development team.

Your Package

• A salary between £58,500 and £63,000 per annum (DOE) plus company bonus.
• Full Time, Permanent contract based at our Newbury Head Office 4 days a week, 1 day working remotely from home
• Holiday Entitlement: 22 days per annum (increasing to 26 days based on tenure) + 8 Bank Holidays, plus buy and sell holiday option AND an annual celebratory day for your birthday.
• Support through our employee assistance programme
• Gym membership and Perkbox subscription

Your Role

• Lead the end-to-end migration of legacy SQL Server databases and ASP.NET applications into Gekko's modern cloud-based platform.
• Analyse existing database structures, stored procedures, application code and business processes to understand dependencies and preserve existing functionality.
• Migrate data and database functionality from Microsoft SQL Server to MySQL, ensuring data integrity and reliable application behaviour.
• Design, develop and maintain backend functionality using C# and .NET Core APIs.
• Build and integrate frontend functionality within the single Angular web application using TypeScript and modern web development practices.
• Replace legacy application logic and direct database dependencies with well-structured APIs and maintainable application components.
• Plan and deliver migrations in manageable stages, minimising disruption to business operations and ensuring existing workflows continue to function correctly.
• Investigate complex technical issues across the database, backend and frontend layers.
• Write clean, efficient and maintainable code, following coding standards and contributing to code reviews and automated testing.
• Document system dependencies, technical decisions and migration processes to support long-term maintenance and knowledge sharing.
• Work with the Lead Architect to agree technical approaches, priorities and delivery plans.

Your Skill Set

• Proven experience as a Senior Full Stack Developer working across database, backend API and frontend application development.
• Strong experience with C#, .NET and modern .NET Core application development.
• Strong hands-on experience with Angular and TypeScript.
• Extensive experience with Microsoft SQL Server, including T-SQL, stored procedures, complex queries and database dependencies.
• Experience with MySQL, including database design, schema migration, indexing and query optimisation.
• Demonstrable experience migrating or modernising legacy applications, databases or business-critical systems.
• Strong understanding of RESTful API design and integration.
• Ability to analyse unfamiliar codebases, understand complex business logic and preserve existing functionality during migration.
• Experience with version control, such as Git, and established software development and testing practices.
• Strong problem-solving and communication skills, with the ability to explain technical decisions and work collaboratively with colleagues and business stakeholders.
• Able to work from our Newbury office four days a week.

Additional Preferred Skills (non-essential)

• Experience migrating legacy ASP.NET Web Forms or MVC applications to modern .NET architectures.
• Experience moving database-driven applications from SQL Server to MySQL.
• Familiarity with Google Cloud Platform, including virtual machines, Cloud SQL, Cloud Storage and Firebase Functions.
• Experience with CI/CD pipelines and automated testing.

Sound Like You?

You enjoy working across the full technology stack and are comfortable tackling complex systems spanning databases, backend services and user interfaces.

You can take ownership of a migration, understand how existing systems work before changing them, and balance modernisation with the need to preserve critical business functionality. You take pride in producing reliable, maintainable software and sharing knowledge to help build a stronger development team.

Gekko Group is a leading field marketing and experiential agency, valuing trust, insight and honesty in all we do. As an inclusive employer, we encourage our teams to grow together in a relaxed but professional environment.

Apply now to help modernise and shape the future of Gekko Group's software platforms.

Pay: £58,500.00-£63,000.00 per year

Work Location: In person