Spain (100% Remote) Seniority: SeniorFULLSTACK JAVA DEVELOPERWe are looking for a Senior Fullstack Java Developer to join one of our clients through an established international IT and business consulting company, with decades of experience delivering large-scale technology and organizational projects across multiple industries.You will work for a leading company in the energy sector, contributing to the development of modern, scalable, and mission-critical systems. The projects focus on cloud-native architectures, event-driven systems, and high-performance platforms that support core energy operations.We are looking for a Senior Fullstack Java Developer with a strong backend focus who is motivated, collaborative, and comfortable working in modern, reactive environments.You will be involved across the full software lifecycle, working closely with agile teams to design and implement tailor-made solutions for complex business processes in the energy domain.As a Fullstack Java Developer, you will:Design, develop, and maintain complex client-facing and backend applicationsWork across the full technology stack, from frontend integration to backend services and cloud environmentsBuild reactive and event-driven systems using modern Java and Spring technologiesCollaborate in agile, cross-functional project teams to deliver customized software solutionsEnsure high standards of code quality, scalability, performance, and reliabilityExtensive experience with Spring Boot, including Spring WebFlux, reactive Kafka Streaming, WebSocket, and Kafka Reactive BinderStrong expertise in database integration, especially PostgreSQL, Hibernate, JDBC, and R2DBC for reactive data processingSolid experience with event-driven architectures, including Kafka as a message brokerExperience integrating Kafka with Spring Boot (e.g. Spring Cloud Stream)Hands-on experience with cloud-native and containerized deployments, including Kubernetes, CI/CD pipelines, and TerraformAbility to deliver clean, scalable, and reliable software within modern reactive technology stacksStrong attention to detail and commitment to high-quality deliveryExperience xohynlm with time-series data processing and time-series databasesInterest in modern development practices and AI-supported tools, with awareness of data protection and compliance requirementsVery good English skills (German is a plus)100% remote workFlexible working hours to support work-life balancePersonalized professional development aligned with your strengths and project interestsAccess to continuous learning platforms and training resourcesLong-term projects in the energy sector, working on impactful and business-critical systemsIf you're interested in building modern, reactive software solutions for the energy sector while enjoying full flexibility and long-term growth, we'd love to hear from you.