Senior low-latency Core Java Developer in London

Contract Role – Senior Low-latency Core Java Developer – London/Hybrid – 12 months initial – Inside IR35

Location: Hybrid – 4 days onsite per week in London

Contract Type: Contract

Duration: 12 months initial

Core focus is hands-on low-latency Java development.

• Exposure to low-latency trading systems in banks or similar institutions.
• Experience building or contributing to low-latency systems.
• Typically around 10+ years overall engineering experience.
• Ideally ~4-5 years working on low-latency systems (flexible if strong elsewhere).
• Has worked on systems handling very high throughput (e.g. billions of events/day).
• Able to design and implement components within a Java-based system.
• Comfortable working in finance/trading environments (FX preferred).
• FX / electronic trading experience (spot, forwards, swaps, execution systems) (preferred).
• Some familiarity with rates or equities environments acceptable.
• Crypto experience is less relevant (not ideal for latency expectations).
• Nice-to-have technologies: KDB (but not required), Solace messaging (nice to have). Kubernetes / cloud / messaging tech (not core focus for this role).
• Has worked in multiple complex production systems (often banking/trading firms).

Must be able to work from a high-level “loose” specification.

Expected to:

• Break down epics into Jira tasks, estimate and plan their own work, work fairly independently.
• Strong hands-on coding role (not architecture-only).

Not looking for:

• Pure microservices / REST-only backend developers.
• Candidates with misleading CVs (claims of low-latency without real experience).
• Pure UI/front-end developers (React/TypeScript not needed).
• Very junior engineers or those with only brief exposure to low-latency systems.