C++ Software Engineer

We’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.

• Modern C++20 and Go on Linux - a modern software stack based on open source
• Cloud-native infrastructure on AWS with colocation in key data centres
• Microsecond-level latency optimisation and high-throughput messaging
• Market-data and reference-data pipelines across multiple asset classes
• FIX protocol integrations with global banks and liquidity providers
• Observability and monitoring - dashboards, alerting, and metrics that make system behaviour visible
• Production systems that handle real money - reliability is not optional

• Strong C++ with Linux systems programming (3+ years)
• Comfortable working close to the metal - you understand what’s underneath your code
• Experience 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 quickly
• Python for scripting, automation, testing, and data analysis - used across the platform for tooling and operational workflows
• Git and shell scripting
• Experience in financial services or trading technology is a plus but not essential

How you work:

• You ship. You’re delivery-focused - you iterate, you improve, you get things into production
• You 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 loop
• You 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 exist
• You communicate. We’re a distributed team across multiple time zones. Clear, proactive communication - especially when things go wrong - is essential
• You care about quality. You write clean, testable code. You review your peers’ work thoughtfully. You push for continuous improvement without gold-plating
• You 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 learn

• An excellent team - senior engineers who care about craft, collaborate openly, and hold each other to high standards
• Ownership - small teams, clear accountability, direct impact on the platform and our clients
• Competitive package - up to 30 days leave + bank holidays, private health insurance, pension, life insurance, dental/optical cashback, cycle to work, socials and offsites
• Remote-friendly - work from home with flexibility. We trust our people to deliver
• Sustainable pace - we work hard, but we don’t burn people out. Balance is how we stay sharp
• Growth - career progression to senior roles, performance specialisation, or technical leadership. We invest in people who invest in us

We 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 sustainable.

We keep our process focused and respectful of your time. Our process follows three stages.

Reactive 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.