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Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Senior Java Developer (AWS/RxJava) - **Company:** UST - **Location:** Madrid, Spain (Remote available) - **Contract:** Permanent contract - **Skills:** Java (Programming Language), Application Programming Interfaces (APIs), Amazon Web Services, Amazon S3, X86-64, Apache HTTP Server, Automation of Tests, Cloud Computing, Cloud Engineering, Continuous Integration, Data Stores, Software Debugging, Software Design Documents, Linux, Distributed Systems, Github, Protocol Buffers, Identity and Access Management, Spring Framework, Junit, Python (Programming Language), PostgreSQL, MongoDB, Pattern Recognition, Redis, Mockito, Rxjava, Spring-boot, Backend, Event Driven Architecture, Integration Tests, Apache Kafka, Reactive Programming, Asynchronous Programming, Teamcity, Grpc, Microservices - **Published:** August 21, 2026 - **Apply:** https://www.tecnoempleo.com/senior-java-developer-aws-rxjava-ust/spring-boot-grpc/rf-d7511594c27a43a26a4c ## About the Role We are seeking a highly skilled Senior Java Developer with extensive experience building scalable, high-performance distributed systems., 8+ years of professional experience with Java development. - 3+ years of hands-on experience with Java 17 or Java 21, including modern language features such as records, sealed classes, pattern matching, and virtual threads when applicable. - Strong expertise in Spring Framework and Spring Boot in production environments. - Proven experience with reactive programming using Project Reactor or RxJava (Mono, Flux, backpressure, retry strategies, hot vs. cold publishers), or advanced asynchronous programming with CompletableFuture and structured concurrency. - Production experience with gRPC and Protocol Buffers, including streaming RPCs, deadlines, interceptors, and schema evolution. - Strong understanding of concurrency fundamentals, executor services, lock-free patterns, and thread lifecycle management. - Solid testing practices using JUnit 5, Mockito, and AssertJ. - Experience developing integration tests against real dependencies and contract/parity testing. - Strong knowledge of Kafka consumer and producer semantics. - Production experience with at least one of the following technologies: Redis, PostgreSQL, or MongoDB. - Cloud experience with AWS (or equivalent cloud platforms), including services such as S3, IAM, managed Kafka solutions, and container runtimes. - Excellent written communication skills with the ability to create design documents, postmortems, and technical documentation. - English level C1 or higher. Nice to Have: - Experience leading large-scale migrations or refactoring initiatives across multi-module codebases. - Knowledge of container packaging and multi-architecture image builds (Linux/AMD64 and Linux/ARM64). - Python knowledge with the ability to read, understand, and debug existing code. - Experience working with Apache Arrow or other columnar data formats. - CI/CD pipeline ownership using TeamCity, GitHub Actions, or similar technologies. - Experience contributing to architecture and technical strategy discussions. ## Description You will join a talented engineering team responsible for designing, developing, and evolving mission-critical applications using modern Java, cloud-native architectures, and event-driven technologies., Design, develop, and maintain robust backend services using Java 17/21 and Spring Boot. - Build scalable and resilient microservices leveraging reactive programming principles. - Develop and maintain gRPC APIs and Protobuf schemas, ensuring backward compatibility and proper schema evolution. - Implement highly concurrent and performant solutions, applying advanced thread-safety and concurrency patterns. - Work with Kafka-based event-driven architectures and production-scale data stores. - Create and maintain automated testing suites, including unit, integration, and contract tests. - Collaborate with cross-functional teams on architecture decisions, design reviews, and technical documentation. - Participate in troubleshooting, root cause analysis, and postmortem activities. - Contribute to CI/CD pipelines, cloud infrastructure, and containerized deployments. - Produce clear technical documentation, design proposals, and pull request descriptions., Nunca debes compartir tus datos bancarios ni fotos de tus documentos al solicitar un empleo. Si tienes alguna duda sobre un proceso de selección En esta oferta serás redirigido a la pagina web de la empresa. Completa el formulario en su web. * Madrid - España Ubicación * Programador Funciones * Jornada completa Jornada * Más de 5 años Experiencia * Indefinido Tipo contrato * gRPC Protobuf ## Related Videos - [Reducing LLM Calls with Vector Search Patterns - Raphael De Lio (Redis)](https://www.wearedevelopers.com/videos/1714-reducing-llm-calls-with-vector-search-patterns-raphael-de-lio-redis) - [How Unit Testing Saved My Career](https://www.wearedevelopers.com/videos/1642-how-unit-testing-saved-my-career) - [Exploring the Power of gRPC-Gateway for Writing RESTful Services](https://www.wearedevelopers.com/videos/2072-exploring-the-power-of-grpc-gateway-for-writing-restful-services) - [Application Modernization and Rabbits](https://www.wearedevelopers.com/videos/120-application-modernization-and-rabbits) - [Accelerating Authentication Architecture: Taking Passwordless to the Next Level](https://www.wearedevelopers.com/videos/733-accelerating-authentication-architecture-taking-passwordless-to-the-next-level) - [From boy scouting to redrawing the landscape](https://www.wearedevelopers.com/videos/1140-from-boy-scouting-to-redrawing-the-landscape) ## Related Articles - [How We Built a Worry-Free System That Runs for 10+ Years – And What We’d Do Again](https://www.wearedevelopers.com/magazine/751-how-we-built-a-worry-free-system-that-runs-for-10-years-and-what-we-d-do-again) - [Fully Remote Software Engineer Jobs](https://www.wearedevelopers.com/magazine/447-fully-remote-software-engineer-jobs) - [Find a Developer Job: 12 Best Job Sites For Developers](https://www.wearedevelopers.com/magazine/165-find-a-developer-job-12-best-job-sites-for-developers) - [Dev Digest 121 - AI goes offline](https://www.wearedevelopers.com/magazine/456-dev-digest-121-ai-goes-offline) - [Top 10 Java Libraries](https://www.wearedevelopers.com/magazine/364-top-10-java-libraries) - [Is Software Engineering Over-Saturated?](https://www.wearedevelopers.com/magazine/418-is-software-engineering-over-saturated)