Java Developer

Job Title: Senior Java Engineer – Low Latency Systems Location: London - 2 days onsite - six-month contract - Outside IR35 - Up to £500 day rate About the Role: We’re looking for a Senior Java Engineer with a passion for low-level, high-performance systems. If you enjoy squeezing out every microsecond of efficiency and building high-throughput, scalable applications, this could be your next immediate move. What You’ll Be Doing Designing and optimising event-driven, non-blocking I/O systems using Java NIO Working with ByteBuffers and direct memory access techniques for optimal performance Developing and maintaining custom binary protocols, ideally with experience in SBE (Simple Binary Encoding) Integrating and fine-tuning Aeron messaging in high-frequency, low-latency environments Conducting performance benchmarking using JMH and other micro-benchmarking tools Tuning JVMs for real-time applications, including GC tuning (ZGC, Shenandoah) and lock-free/wait-free structures Collaborating closely with architecture teams to ensure garbage-free, latency-critical design What We’re Looking For Core Low-Latency Engineering Experience Strong command of Java NIO, selectors, channels, and event loops Deep understanding of ByteBuffer usage, memory alignment, and off-heap data structures Experience with binary protocols (fixed-width encoding, custom parsers, etc.) Hands-on expertise with Aeron or similar low-latency transport layers Performance Engineering Knowledge Familiarity with threading models like epoll, reactor pattern Use of lock-free/wait-free data structures in production JVM internals expertise – GC tuning, heap sizing, latency profiling Benchmarking experience with JMH, latency histograms, flame graphs If this sounds like the kind of challenge you're looking for, hit apply or reach out directly for a confidential chat!