Low Latency Java Engineer

Citi; Greater London; On-site; GBP 110,000 - 140,000; Full time

Benefits offered by this job

27 days annual leave

Discretional annual bonus

Private Medical Care & Life Insurance

Employee Assistance Program

Pension Plan

Paid Parental Leave

Special discounts

Learning & development resources

Job summary

Citi is seeking a senior Low Latency Java Engineer to drive Java-based, low-latency systems for algorithmic trading. You will develop event-sourced microservices, influence architecture decisions, and collaborate with cross-functional teams in a high-performance London environment.

You will mentor junior engineers while shaping core trading platforms, with a focus on market data, latency reduction, and scalable design.

Qualifications

• SME in Applications Development.
• Experience with Algorithmic Trading development in low latency environments.
• Experience with Market Data handling and related tech (KDB).
• Demonstrated leadership and project management skills.
• Proficient in modern Java, JVM, Linux, system calls and kernel.
• Knowledge of TCP/IP and kernel bypass tech (Solarflare OpenOnload).

Responsibilities

• Hands-on work in Java or Rust within a low-latency microservices framework (response times 10–100 µs).
• Lead integration of functions to meet goals, deploy new products, and enhance processes.
• Analyze complex business and system processes to define high-level solutions.
• Provide World class expertise in Java low-latency development.
• Mentor junior developers and less experienced seniors.

Skills

Java

Low latency

Algorithmic trading

KDB

Market data

C++

UML

Job description

Low Latency Java Engineer

Engineer the future of global finance. At Citi, our Tech team doesn’t just support finance – we are helping to redefine it. Every day, $5 trillion crosses through our network. We do business in 180+ countries operating at a scale few can match. From deploying advanced AI to helping shape global markets, we build systems that matter. Look to join a team where your work helps influence economies, your ideas can drive innovation and outcomes, and your growth is backed by mentorship, continuous learning and flexibility with potential hybrid work opportunities. Help solve real-world challenges that touch millions and get the opportunity to build the future of finance with Citi Tech.

What We do / The Team

This is a senior level position responsible for establishing and implementing new or revised application systems and programs in coordination with the Technology Team. The overall objective of this role is to lead applications systems analysis and programming activities.

The role is to provide senior, low-latency systems and application framework engineering (skilled in Java, C++ , Rust, KDB, market data, algorithmic trading technology) within the London Based High Performance Architectures (HPA ) team. The team require a specialist on algorithmic trading systems utilities including but not limited to market data replay and back test/simulation utilities. The HPA organization are a high skilled enablement group of Subject Matter experts - who produce application frameworks and engage with application engineers to enable application Modernisation to over 100 teams across Citi with a concentration on low latency eTrading platforms in Markets Technology.

Responsibilities include (but not limited to):

• 90% hands in the Java or Rust codebase. We build microservices based event sourcing systems on a low latency in-house framework. Response times in the 10 microsecond to 100 microsecond range.
• Lead integration of functions to meet goals, deploy new products, and enhance processes
• Analyse complex business processes, system processes, and industry standards to define and develop solutions to high level problems
• Provide world class expertise in area of Java low latency development.
• Utilize advanced knowledge of supported main system flows and comprehensive knowledge of multiple areas to achieve technology goals
• Consult with end users to identify system function specifications and incorporate into overall system design
• Influence and negotiate with senior leaders and communicate with external parties
• Happy to work with and educate and support/mentor Junior developers and less experienced senior Java developers.

Key Skills and Experience required

• Demonstrated Subject Matter Expert (SME) in area(s) of Applications Development
• In-depth experience with Algorithmic Trading application development, preferably in low latency environment
• Detailed comprehension and experience with Market Data handling and associated technologies (such as time-series databases e.g. KDB)
• Demonstrated leadership, project management, and development skills
• Passion for coding excellent, commercial grade, mission critical Java frameworks based on event sourcing microservices.
• Complete knowledge of modern Java, the JVM, the Linux Operating system, system calls and Kernel.
• Knowledge of TCP and other IP based network protocol technologies including hardware accelerated kernel bypass e.g. Solarflare OpenOnload
• Performance assessment and targeted tuning.
• Design and architectural elegance.
• Experience in implementing projects
• Great communicator with high EQ.
• Ability to occasionally produce clear diagrammatic documentation and model key aspects in UML sequence diagrams.
• Relationship and consensus building skills

Nice to have

• Background in C++

This job description provides a high-level review of the types of work performed. Other job-related duties may be assigned as required.

What we’ll provide you

• 27 days annual leave (plus bank holidays)
• A discretional annual performance related bonus
• Private Medical Care & Life Insurance
• Employee Assistance Program
• Pension Plan
• Paid Parental Leave
• Special discounts for employees, family, and friends
• Access to an array of learning and development resources

Visit our Global Benefits page to learn more.

Alongside these benefits Citi is committed to ensuring our workplace is where everyone feels comfortable coming to work as their whole self, every day. We want the best talent around the world to be energized to join us, motivated to stay and empowered to thrive.

Job Family Group: Technology

Job Family: Applications Development

Time Type: Full time

Most Relevant Skills: Please see the requirements listed above.

Other Relevant Skills: For complementary skills, please see above and/or contact the recruiter.

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