Senior Java Engineer, freelancer

About this role

About Espeo Software

We are a technology company that started its journey in 2008. For more than 17 years, we have been assisting companies in developing and implementing innovative fintech solutions. Leveraging our expertise in areas such as blockchain, online payments, and more, our clients can invent and develop cutting-edge solutions and services that keep them at the forefront of innovation. About the opportunity: This role gives you ownership of core backend services, technical challenges, and collaboration with Product, Web, Mobile (React Native), and DevOps teams across Europe. You’ll also have the opportunity to adopt modern tools, including AI-assisted development, and help shape engineering practices. What you’ll be doing: Design, build, and maintain high-quality Java Spring Boot microservices within a domain-bounded architecture Implement event-driven architecture for cross-domain communication and eventual consistency Work with PostgreSQL, including schema design, multi-tenancy, indexing, query optimization, and transaction management Implement RESTful APIs with versioning, rate limiting, and API gateway integration Ensure code quality, performance, security, and comprehensive testing (unit, integration, contract) Collaborate with Product, Web, Mobile (React Native), DevOps, and other backend teams across multiple European markets Participate in architectural discussions, technical design reviews, and contribute to platform-wide standards Take ownership of service reliability and operability, proactively reducing technical debt Leverage AI-native development tools (Copilot, Cursor, Claude) to accelerate delivery and improve code quality Support a “you build it, you run it” mindset for reliable delivery and smooth operations Skills we’re looking for: 6+ years of professional software development experience Strong expertise in Java (1