C++ Software Engineer

C++ Software EngineerRemote (UK-based) | Full-TimeAbout UsReactive Markets is the 2026 OTC Trading Platform of the Year (Risk.net). Our network handles over $50 billion in daily trading volumes across FX, Equities, and Cryptocurrency, connecting 40+ of the world's leading liquidity providers.We build trading systems that operate at the edge of what's technically possible — where nanoseconds matter and a dropped message costs real money. Our engineering team is small, senior, and deeply invested in the craft of building cutting edge, reliable, high-performance systems.The RoleWe're looking for a C++ Software Engineer who wants to build low-latency trading infrastructure on Linux. You'll work on the core components of our Switchboard trading platform — pricing engines, connectivity gateways, market-data systems, and the messaging layer that ties them together.This is not a role where you write code and throw it over a wall. You build it, you test it, you deploy it, you support it in production, and you improve it. Our engineers own the full lifecycle — from design through to operational excellence. When something breaks at 4pm on a Friday, you're part of the team that investigates and fixes it.Occasional hours outside the normal working day are required for production releases, scheduled maintenance windows, and Level 3 support during critical incidents. We keep this to a minimum and recognise the commitment — but owning a production trading platform means being there when it matters.What You'll Work OnModern C++20 and Go on Linux — a modern software stack based on open sourceCloud-native infrastructure on AWS with colocation in key data centresMicrosecond-level latency optimisation and high-throughput messagingMarket-data and reference-data pipelines across multiple asset classesFIX protocol integrations with global banks and liquidity providersObservability and monitoring — dashboards, alerting, and metrics that make system behaviour visibleProduction systems that handle real money — reliability is not optionalWhat We NeedTechnical:Strong C++ with Linux systems programming (3+ years)Comfortable working close to the metal — you understand what's underneath your codeExperience with performance-sensitive systems (profiling, optimisation, deterministic behaviour)Familiarity with networking fundamentals (TCP/UDP, socket programming)Go experience is a strong bonus — we use Go extensively for microservices and command-line tooling, and you'll be expected to work with it internally. If you don't know it yet, strong C++ engineers pick it up quicklyPython for scripting, automation, testing, and data analysis — used across the platform for tooling and operational workflowsGit and shell scriptingExperience in financial services or trading technology is a plus but not essentialHow you work:You ship. You're delivery-focused — you iterate, you improve, you get things into productionYou own it. When you build something, you take responsibility for its behaviour in production. You respond to incidents (15-minute acknowledgement SLA during working hours), investigate issues, and close the loopYou write things down. Documentation is not an afterthought — it's how we scale knowledge across a distributed team. If it's not written down, it doesn't existYou communicate. We're a distributed team across multiple time zones. Clear, proactive communication — especially when things go wrong — is essentialYou care about quality. You write clean, testable code. You review your peers' work thoughtfully. You push for continuous improvement without gold-platingYou embrace AI tooling. We use AI tools (Claude, Gemini) to amplify our engineering capability — from code review and debugging to incident investigation and documentation. You don't need to be an expert, but you should be curious and willing to learnWhat You GetReal problems —trading systems where performance is measured in microseconds, not user clicksAn excellent team — senior engineers who care about craft, collaborate openly, and hold each other to high standardsOwnership — small teams, clear accountability, direct impact on the platform and our clientsCompetitive package — up to 30 days leave + bank holidays, private health insurance, pension, life insurance, dental/optical cashback, cycle to work, socials and offsitesRemote-friendly — work from home with flexibility. We trust our people to deliverSustainable pace — we work hard, but we don't burn people out. Balance is how we stay sharpGrowth — career progression to senior roles, performance specialisation, or technical leadership. We invest in people who invest in usWe believe in transparency, honest feedback, and writing things down. We celebrate delivery, not activity. We frame AI as empowering people — removing toil, amplifying capability, enabling higher-value work.We aim to build systems that don't depend on the heroics of individuals to maintain and support — systems and processes that are resilient, documented, and sus