Our client, a leading hedge fund, is seeking a Low-Latency C++ Software Developer to join their Order Entry Gateway team in London. This role is focused on building and optimising the core execution pathway that routes orders to global trading venues, where deterministic performance, resilience under peak volatility, and correctness are absolutely critical. To be successful, you will bring strong hands-on experience engineering high-performance C++ systems on Linux, with a solid understanding of networking, concurrency, and latency profiling. You'll work closely with engineers, trading stakeholders, and platform partners to improve throughput, reduce tail latency, and ensure the gateway remains robust and observable as the firm scales. Responsibilities: Design, build, and optimise a low-latency order entry gateway. Develop and maintain exchange connectivity (FIX and/or binary protocols), including on-boarding new venues and improving message handling. Drive latency improvements through profiling, performance tuning, and architectural refinement. Contribute to engineering best practices: code quality, testing strategy, and deployment safety in a fast-moving environment. Requirements: Strong modern C++ (C++17/20) with demonstrable experience building high-throughput, low-latency systems. Strong Linux systems knowledge. Strong concurrency, multi-threading fundamentals. Solid networking experience (message framing/serialisation; low-latency network considerations). Experience with order routing, market access, execution gateways (or adjacent ultra-low-latency domains).