Senior Java Developer (RxJava) | Freelance (Remote, 30-33€/h)
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Summary
Freelance senior Java developer role (remote from Spain, €30-33/hour) building scalable, reactive microservices for a banking-sector client. Day-to-day work spans Java 17/21, Spring Boot, RxJava/Project Reactor, gRPC, Kafka, Redis, PostgreSQL, MongoDB, AWS and Docker/CI-CD, hired through outsourcing firm SQUAD Technology Solutions.
AAt SQUAD Technology Solutions, an IT outsourcing company, we are building a small, agile team with a strong commitment to doing things right from the very beginning.
We are currently working with one of our clients to hire a Java Senior Developer with reactive programming for a project in the banking sector.
What are we looking for?
- 8+ years of Java development experience, including Java 17/21, modern language features, concurrency, and high-performance backend systems.
- Strong expertise with Spring Boot, Project Reactor, RxJava, and CompletableFuture to build scalable and reactive microservices.
- Hands-on experience with gRPC & Protobuf, including streaming RPCs, interceptors, deadlines, and API/schema evolution.
- Solid background in Kafka, Redis, PostgreSQL, and MongoDB, delivering event-driven and data-intensive applications.
- Strong cloud experience on AWS (S3, IAM, Managed Kafka, container runtimes) and modern distributed architectures.
- Expertise in Docker, multi-architecture container images (amd64/arm64), CI/CD, and cloud-native deployment practices.
- Experience leading large-scale refactoring or migration projects in multi-module codebases, with strong communication skills and C1 English; Python knowledge is a plus.
What are we offering?
- Freelance contract with immediate onboarding.
- Stable and full time project with an international client.