More in detail, UST is a multinational company based in North America, certified as a Top Employer and Great Place to Work company with over 35,000 employees worldwide and presence in more than 35 countries. We are leaders in digital technology services, providing large-scale technological solutions to some of the world's most renowned organizations. We are seeking a highly skilled Senior Java Developer with extensive experience building scalable, high-performance distributed systems.
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.
Develop and maintain gRPC APIs and Protobuf schemas, ensuring backward compatibility and proper schema evolution.
Work with Kafka-based event-driven architectures and production-scale data stores.
Create and maintain automated testing suites, including unit, integration, and contract tests.




Participate in troubleshooting, root cause analysis, and postmortem activities.
Contribute to CI/CD pipelines, cloud infrastructure, and containerized deployments.
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. 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.
Redis, PostgreSQL, or MongoDB.
Cloud experience with AWS (or equivalent cloud platforms), including

📌 Senior Java Developer (Valencia)
🏢 UST España & Latam
📍 Valencia