Senior Low Latency Engineer - Citi in London

Working at Citi is far more than just a job. A career with us means joining a team of more than 230,000 dedicated people from around the globe. At Citi, you'll have the opportunity to grow your career, give back to your community and make a real impact.

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 application 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 HPA organization is a high‑skill 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 e‑Trading platforms in Markets Technology.

Responsibilities

• 90% hands‑on 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 Java low‑latency development.
• Utilise 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

• Demonstrated subject‑matter expert (SME) in application 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 (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++.

What We’ll Provide You

• 27 days annual leave (plus bank holidays).
• A discretionary 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.

Citi is an equal‑opportunity employer, and qualified candidates will receive consideration without regard to their race, color, religion, sex, sexual orientation, gender identity, national origin, disability, status as a protected veteran, or any other characteristic protected by law.

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