Senior Software Engineer

Senior Java Developer UK – Hybrid (3 days onsite) Java, Spring Boot, Microservices, Cloud, TDD, Capital Markets, Post-Trade The Company This is a rare opportunity to join a specialist post-trade technology firm operating at the heart of the capital markets space. Trusted by some of the most sophisticated participants in the industry, this business has built a reputation for delivering mission-critical clearing and prime brokerage technology that demands both precision and performance. The engineering team is lean, expert and highly collaborative — with a culture that treats technology as a genuine business differentiator rather than a support function. The Opportunity As a Senior Java Developer, you will take a central role in building and evolving the firm's post-trade technology platform — including in-house systems, APIs, client reporting tools and the client web portal. You will also be responsible for customising and extending a third-party trading system to meet complex business requirements. Working closely with Client Services and Product Management, you will translate demanding, real-world requirements into scalable, high-quality software solutions. What You'll Be Doing Designing, developing and maintaining in-house systems, APIs, reporting tools and the client web portal Customising and extending third-party trading systems to meet business requirements Writing clean, well-tested, production-grade code following SOLID principles, Design Patterns and Clean Code practices Applying TDD and BDD methodologies using JUnit, Spock and Mockito Contributing to and improving code review standards across the team Liaising directly with Client Services and Product Management to understand requirements and propose solutions Managing and mentoring a small team of Java developers, supporting their growth and career development Working alongside offshore developers, maintaining clear communication across time zones Leveraging AI tooling within the SDLC to drive productivity and quality What We're Looking For 7+ years' Java development experience within a Financial Services firm Strong hands-on expertise in Java 11+, Spring/Spring Boot, multithreading, performance tuning and RMI Capital Markets domain knowledge — Clearing, Prime Brokerage or similar post-trade experience Solid grounding in TDD, BDD, Agile and automated builds/deployments Experience with CI/CD toolchains (GitHub, Azure DevOps, Jenkins) and deployment management Proficiency with Git, Maven, JUnit/Spock and Mockito Microservices architecture knowledge Strong understanding and application of SOLID, Design Patterns and Clean Code Ability to communicate clearly with both technical peers and non-technical stakeholders Cloud platform exposure (AWS, Azure or GCP) Desirable: Groovy, FpML, FIX/FIXML, REST, JSON, Message Queuing Desirable: experience leading a developer team or working with offshore teams Right to work in the UK without sponsorship What's on Offer Up to £125,000 basic Performance-related bonus Hybrid working – 3 days per week onsite Private healthcare, pension, life assurance and critical illness cover 100% cloud-based, modern tech stack with Azure AI Cognitive Services integration A business that values engineering as a core differentiator Find Out More If you would like to have a confidential conversation and find out more about this opportunity, please get in touch with Con Lam at Harrington Starr, or click the apply button below.