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Java Engineer - Backend - Distributed Systems

London, UK - Excellent
Contract
Posted by Rothstein Recruitment Ltd
Applicants must be eligible to work in the specified location

Java Engineer - Backend - Distributed Systems

Excellent opportunity opens for talented Java Developers to join a Globally leading Financial Services entity, working on critical, new projects.

Role overview

We are hiring Back End Java engineers to work on large-scale, event-driven platforms processing high volumes of Real Time transactions and API traffic. The environment is fully reactive and non-blocking, built for throughput, resilience, and low latency. This is not traditional Spring MVC/CRUD development. The stack is based on reactive streams and distributed data stores.

Key responsibilities

  • Build and maintain reactive microservices using Project Reactor (Flux/Mono)
  • Develop APIs and services using Spring WebFlux and non-blocking I/O
  • Design and optimise data models on Apache Cassandra for scale and resilience
  • Work with event-driven architectures (typically Kafka or similar messaging)
  • Focus on performance, fault tolerance, and horizontal scalability
  • Collaborate with platform, SRE, and data teams on production systems running at scale

Required experience

  • Strong Java Back End engineering background (Java 11+)
  • Hands-on production experience with Project Reactor and reactive programming
  • Experience building services with Spring WebFlux (not only Spring MVC)
  • Experience working with Cassandra or other distributed NoSQL databases
  • Understanding of:
  • Non-blocking I/O
  • Backpressure
  • Reactive threading models
  • Experience in high-throughput, low-latency systems (payments, trading, telco, fintech, large-scale APIs)

Desirable experience

  • Kafka or other streaming platforms
  • Reactive database drivers (eg, reactive Cassandra, R2DBC)
  • Cloud platforms (AWS, GCP, or Azure)
  • Kubernetes and containerised deployments
  • Observability in reactive systems (metrics, tracing, resilience patterns)

Interested? Please Apply!

London, UK
IT
ASAP, will await notice
12 months initial Duration
Excellent
Rothstein Recruitment Ltd
Will Buckner
02076007888
JS/MRL/WB/JAVACONTRACTORS
22/01/2026 10:50:26