Lead Java Developer

Cpl; Greater London; Hybrid; GBP 112,000 - 147,000; Full time

Job summary

CPL is seeking an experienced Lead Java Developer to join a high-performing team in London on a 4-month hybrid contract. The role focuses on ultra-low-latency, high-throughput trading and risk platforms, collaborating with traders and quantitative teams to deliver scalable solutions.

You will design, develop, and optimise Java applications with a strong emphasis on performance, JVM tuning, and concurrent programming in a fast-paced front-office environment.

Qualifications

• Proven experience with core Java and low-latency development.
• Deep understanding of JVM tuning, GC optimization and performance.
• Strong knowledge of data structures, algorithms and concurrent programming.
• Experience building event-driven, reactive and high-frequency systems.
• Knowledge of TCP/UDP networking and Linux internals.

Responsibilities

• Design and build high-performance, low-latency Java applications.
• Develop event-driven and reactive systems for high transaction volumes.
• Optimize application performance through JVM tuning and GC strategies.
• Work on highly concurrent systems focusing on scalability and throughput.
• Collaborate with global teams on trading and risk platform initiatives.

Skills

Core Java

Low latency

JVM tuning

Data structures & algorithms

Concurrency

Event-driven systems

TCP/UDP networking

Job description

Lead Java Developer (Low Latency Trading Systems)

Contract: 4 Months

Rate: Up to £700 per day

Location: Hybrid - London

IR35: Inside IR35

The Opportunity

We are looking for an experienced Lead Java Developer to join a high-performing team delivering strategic Agency Liquidity and Principal Risk initiatives across EMEA and North America. This is an exciting opportunity to work on business-critical trading and risk platforms where performance, scalability and reliability are paramount.

You will play a key role in the design, development and optimisation of ultra-low-latency, high-throughput systems, working alongside traders, quantitative teams and technology stakeholders in a fast-paced front-office environment.

Key Responsibilities

• Design and build high-performance, low-latency Java applications.
• Develop event-driven and reactive systems capable of handling high transaction volumes.
• Optimise application performance through advanced JVM tuning and garbage collection strategies.
• Work on highly concurrent systems with a focus on scalability, resilience and throughput.
• Collaborate with global teams to deliver strategic initiatives across trading and risk platforms.
• Analyse and improve system performance across the full technology stack, from application code to infrastructure.

Required Skills & Experience

• Strong commercial experience with Core Java and low-latency application development.
• Deep understanding of JVM tuning, garbage collection and performance optimisation.
• Expertise in data structures, algorithms and concurrent programming.
• Proven experience building event-driven, reactive and high-frequency systems.
• Strong knowledge of TCP/UDP networking, Linux internals and distributed systems.
• Understanding of CPU architecture, memory management, shared memory and memory-mapped files.
• Experience working with technologies such as JNI, Java Unsafe, JNR-FFI and similar performance-focused frameworks.
• Experience with Aeron messaging technology.
• Background within investment banking, electronic trading, market data, pricing, liquidity or risk platforms.
• Knowledge of front-office trading environments and real-time financial systems.