Senior/Principal Java Engineer - Low Latency

JUXT; Greater London; On-site; GBP 90,000 - 150,000; Full time

Job summary

JUXT is seeking Senior and Principal Java Developers to work on a high-performance trading and real-time data project for a major financial institution. You will write and tune Java frameworks, optimise throughput and latency, and apply event-driven, microservice-based architectures.

You will join a team that values clean design, measurable performance, and deep system understanding, contributing to systems that power global trading platforms and real-time data services.

Qualifications

• Strong Java skills with deep knowledge of the JVM.
• Experience building or optimising low-latency systems.
• Proficient with multithreading, memory management and profiling tools.

Responsibilities

• Write and tune high-performance Java frameworks to improve throughput and latency.
• Apply event-driven, microservice-based architectures on mission-critical applications.
• Collaborate with engineers to shape elegant, performance-focused solutions.
• Maintain and improve systems that power real-time trading and data platforms.

Skills

Java

Low-latency systems

Multithreading & concurrency

Performance tuning

Linux fundamentals

Microservices & event-driven

Communication skills

Tools

JMH

async-profiler

Flight Recorder

Kafka tuning

Netty

Chronicle Queue

Aeron

Job description

We're looking for Senior and Principal Java Developers with a strong background in low-latency systems to join us on a high-performance trading and real-time data project, for a major financial institution.

You'll work on mission-critical applications where performance, scalability, and reliability truly matter 6 the kind of systems that power global trading platforms and require a deep understanding of how the JVM and Linux really work. This is an opportunity to bring world-class engineering principles to projects at the very heart of modern finance.

Your work will focus on writing and tuning high-performance Java frameworks, improving throughput and latency, and applying event-driven, microservice-based architectures. You'll collaborate closely with other talented engineers, helping to shape elegant solutions to complex, performance-sensitive problems.

You'll be joining an environment where good software engineering truly matters 6 where clean design, measurable performance, and deep system understanding are valued. This is an opportunity to work alongside recognised low-latency specialists, elevate your expertise, and contribute to systems that demand precision and technical excellence.

We're looking for developers who are technically exceptional, but also pragmatic 6 engineers who love to understand how things work under the hood, measure performance precisely, and continuously refine their craft.

Core Skills

• Strong Java skills with deep knowledge of the JVM
• Proven experience building or optimising low-latency systems
• Familiarity with performance tuning and profiling tools (e.g. JMH, async-profiler, Flight Recorder)
• Solid understanding of multithreading, concurrency, and memory management
• Experience with microservice architectures and event-driven systems
• Strong Linux fundamentals and comfort with performance diagnostics
• Clear communication skills and ability to articulate design and performance decisions

Nice To Have

• Experience with high-performance messaging (Chronicle Queue/Wire, Aeron, ZeroMQ, Kafka tuning)
• Familiarity with off-heap or direct memory structures (Chronicle Map, VarHandles, DirectByteBuffers)
• Networking/I/O frameworks such as Netty or custom FIX engines
• Exposure to OpenHFT, LMAX Disruptor, or similar performance-focused frameworks
• Prior experience in trading, financial markets, or real-time data systems
• Ability to produce clear, lightweight documentation or UML diagrams when needed