Senior Software Engineer (Java)

This full-time position in London involves designing and maintaining secure, high-performance backend systems for a rapidly expanding fintech company. Daily tasks center on greenfield development and enhancing existing infrastructure, specifically through the creation of REST APIs and microservices. You will work on critical business systems such as card payments, treasury management, transaction booking, and crypto liquidity. The technical environment relies heavily on Java 25 and Postgres, utilizing Spring Boot to facilitate efficient delivery. The team adheres to clean code principles, employing test-driven development, domain-driven design, and continuous integration practices to ensure maintainability. Candidates must possess demonstrable backend experience with fluency in Java, alongside a bachelor’s degree or higher in computer science, mathematics, physics, or a related engineering field. The role requires a quick learner with strong verbal and written English communication skills. It is ideal for ambitious, results-driven professionals who have a track record of building complex products used by millions at hypergrowth startups. The company emphasizes that every team member helps shape the product and culture during this early stage of growth.