Were hiring a Senior Software Engineer (Python) - Trading Systems to own and evolve a production options trading system. It runs during market hours, ingests real-time market data, and requires profiling-led performance engineering to keep p50/p99 latency, jitter, and reliability within tight bounds. Youll take meaningful ownership day-to-day, partnering closely with the founder and the engineering team to prioritise work, ship improvements quickly, and keep the system fast, reliable, and correct. Who this is for This role is for engineers who have built and owned real-time, performance-critical systems. It is not suitable for candidates whose experience is mainly web product development (frontend-heavy or CRUD backends). Were looking for proven experience with measuring and improving p99 latency/jitter and operating systems during time-critical windows. Must be based in the UK and with a legal right to work in the UK Location : UK-based Working style : Mostly remote, occasional in-person days for planning/coordination Support : Availability during core market hours required What Youll Do Own and improve a production Python codebase that runs during market hours. Build and optimise real-time market data pipelines (throughput, p50/p99 latency, jitter). Do profiling-driven performance work across ingestion ? compute ? messaging ? consumers. Improve reliability: freshness/staleness handling, safe degradation, back pressure, fault isolation. Strengthen developer leverage: replay/simulation tools, regression tests, and debugging tooling. Work with cloud infrastructure, deployment, monitoring, and incident response. Collaborate directly with the founder and engineering team on architecture and roadmap. Essential Skills 5 years professional Python experience; youve shipped and owned production systems. Built/owned a real-time / low-latency system (not batch ETL) with measurable performance goals. Strong understanding of async multiprocessing trade offs and performance profiling. Comfortable owning an existing codebase: refactors, tests, architecture improvements. Experience with messaging / event-driven systems and strong API/schema discipline. Production ownership mindset: incidents, monitoring, and fast debugging when it matters. UK-based preferred and able to support core market hours when required. Desirable Skills Interactive Brokers (TWS/IB Gateway) or similar brokerage/execution APIs. Experience with trading, market data, or execution systems. Experience designing safety constraints/guardrails in automated systems. What We Offer Competitive salary (negotiable) performance-related bonus. Mostly remote, with some in-office collaboration days for coordination and planning Lean environment, direct impact on a live system. High ownership and influence over system design and roadmap.