Software Engineer in Slough

Senior Software Engineer – Application Modernization (Contract)

About the Role:

We’re looking for a hands-on software engineer to help modernize a suite of critical financial applications that support Reference Data, the backbone of trading and market workflows. This role offers the chance to upgrade legacy systems, improve reliability, and ensure data-driven systems remain secure and maintainable for the future.

Responsibilities:

• Take legacy applications written in Kotlin, Java, and C# and bring them up to modern standards
• Review and understand existing systems to identify areas for improvement
• Plan and execute upgrades, ensuring seamless integration and minimal disruption
• Collaborate with engineers and stakeholders to maintain high code quality, security, and performance
• Document improvements and share knowledge to strengthen the team’s long-term capabilities

What you\’ll need:

• Strong experience in Kotlin, Java, and/or C#, ideally in production systems
• Familiarity with modern JVM frameworks (Spring Boot, etc.) and legacy .NET applications
• Experience upgrading or modernizing older systems in a structured, methodical way
• Skilled at testing, integration, and troubleshooting in live environments
• Proactive, detail-oriented, and able to take ownership of complex systems