Java Consultant

Senior Java / Java & C++ Developer – Low Latency & JVM Performance

Location: London, UK (Hybrid – 3–4 Days Onsite per Week)

Contract Duration: 12 Months

Employment Type: Contract

Industry: Investment Banking / Financial Services

Job Description

We are looking for highly experienced Senior Java Developers and Java/C++ Developers with strong expertise in JVM performance tuning, low-latency systems, high-performance computing and real-time financial applications.

The successful candidates will work on complex, performance-critical platforms requiring advanced Java development, concurrency, memory optimization and efficient network communication.

Key Responsibilities

• Design, develop and optimize high-performance, low-latency applications using Core Java and, where applicable, C++.
• Perform JVM performance tuning, garbage collection optimization and memory management.
• Develop event-driven, reactive and multithreaded applications with high throughput and minimal latency.
• Design efficient algorithms and data structures for performance-critical workloads.
• Work with advanced Java technologies such as JNI, Java Unsafe, JNR-FFI and memory-mapped files.
• Optimize networking, messaging and inter-process communication using TCP/UDP, shared memory and Linux-based systems.
• Develop and support real-time market data processing, trading and financial applications.
• Collaborate with architects, developers and business stakeholders to deliver reliable, scalable solutions.

Mandatory Technical Requirements

• 8–10+ years of professional software development experience, with strong hands-on Core Java expertise.
• Strong practical experience in JVM tuning, GC optimization and Java performance engineering.
• Experience developing low-latency or high-performance applications.
• Strong knowledge of multithreading, concurrency, memory management, data structures and algorithms.
• Experience with event-driven systems, networking and Linux environments.
• Understanding of CPU architecture, shared memory, memory-mapped files and TCP/UDP communication.
• Experience with C++ and low-level network programming is required for the Java/C++ position.
• Strong analytical, troubleshooting and problem-solving skills.

Desirable Skills

• Aeron messaging framework.
• JNI, Java Unsafe and JNR-FFI.
• Kernel-bypass networking.
• High-frequency trading (HFT), electronic trading and market data systems.
• EMEA direct feeds and US options market data.
• MiFID II market structure.
• Denali, MPAC, Beacon or Refinitiv ETA distribution protocols.