Senior Java Software Engineer in City of London

A leading global investment management firm is seeking Senior Software Engineers (Contract) to join its Market Data Platform team on a high-impact engagement. This is a critical hire, with the opportunity to step into a highly visible area of the business where performance, scale and reliability truly matter.

This team sits at the heart of a systematic trading environment, responsible for ingesting and processing vast volumes of real-time market data through direct exchange connectivity. The platform operates at extreme scale - handling 15–20 billion data points per day, with peak rates of over 1 million events per second - and accuracy is non-negotiable.

This opportunity would suit an engineer with deep Java expertise who has worked on complete data platforms, particularly those handling real-time or market data using Kafka.

The Role

• Designing, developing and optimising components of a large-scale data platform used across the investment business.
• Building and evolving end-to-end data platforms supporting real-time and historical data use cases.
• Developing primarily in Java, with Python used across parts of the wider platform.
• Working extensively with Kafka and streaming architectures to handle real-time data flows.
• Contributing to systems processing billions of events per day, with peak throughput in the millions per second.
• Improving and modernising existing components, with a strong focus on latency, scalability and resilience.
• Partnering closely with data management teams, quantitative researchers and other engineering groups.
• Taking ownership of production systems, from requirements gathering through to deployment and optimisation.

Required Experience

• Extensive commercial Java development experience, particularly on backend or data-intensive systems.
• Demonstrable experience building or contributing to complete data platforms.
• Hands-on experience working with real-time data, ideally using Kafka.
• Background in market data, trading systems or other time-sensitive data domains is highly desirable.
• Strong Python skills used in production environments.
• Solid experience working on Linux and strong understanding of Git.
• Experience with databases or data storage technologies such as MongoDB, Postgres, Iceberg or similar.
• Comfortable working in fast-paced, performance-critical environments.
• Strong problem-solving skills, attention to detail and ability to work autonomously.

Advantageous to Have

• Experience with distributed systems and large-scale data processing.
• Performance tuning and optimisation of low-latency systems.
• Exposure to orchestration frameworks and modern data infrastructure.
• Contributions to open-source projects.
• Experience working with or around Large Language Models (LLMs).

Rate: £500-575 per day (Inside IR35 – some flexibility for the right candidate)

Location: Hybrid – 3 days per week onsite in the City of London.

Start: ASAP

Interview Process

• 30-minute introductory discussion with the hiring manager.
• 1-hour technical / programming interview with a team member.
• Possible final 30-minute follow-up; we expect at least 1 interview conducted in person.