Senior Software Engineer

Senior C++ Software Engineer

Remote (UK) | Full-Time

Build Trading Systems Where Microseconds Matter

Shape the future of electronic trading at Reactive Markets , the 2026 OTC Trading Platform of the Year (Risk.net) .

Our platform handles $50+ billion in daily trading volume across FX, Equities and Crypto, connecting more than 40 of the world's leading liquidity providers . Every day, our technology powers mission-critical trading infrastructure where reliability, scalability and performance directly impact financial markets.

We're looking for an experienced Senior C++ Software Engineer to join our engineering team and help build systems operating at the limits of performance. This is an opportunity to work on complex distributed systems, ultra-low latency architecture and high-throughput messaging platforms while influencing the technical direction of a rapidly growing business.

If you're passionate about modern C++, Linux, distributed systems and solving hard engineering problems, we'd love to hear from you.

Why Join Reactive Markets?

• Work on systems processing $50bn+ daily trading volume
• Influence architecture and technical direction
• Modern stack: C++20, Go, Linux, AWS
• Fully remote UK opportunity
• Small, senior engineering team with high autonomy
• Direct ownership from design through production
• Competitive package with comprehensive benefits

The Opportunity

As a Senior C++ Engineer, you'll play a key role in evolving our award-winning Switchboard trading platform .

You'll design, build and optimise performance-critical systems including:

• Pricing and execution engines
• Market data and reference data platforms
• Connectivity gateways and FIX integrations
• High-performance messaging infrastructure
• Low-latency distributed systems
• Cloud-native services running on AWS

This is a true ownership role. You'll be involved throughout the entire software lifecycle, from architectural design and implementation through to deployment, observability and production support.

Alongside hands-on engineering, you'll help shape technical strategy, mentor teammates and contribute to the standards that underpin a world-class trading platform.

What You'll Be Working With

• Modern C++20
• Go
• Linux systems programming
• AWS cloud infrastructure
• Python
• Git & Shell Scripting
• FIX Protocol
• TCP/UDP Networking
• Distributed Systems Architecture

Engineering Challenges

• Microsecond-level latency optimisation
• High-throughput messaging systems
• Large-scale market data processing
• Real-time trading infrastructure
• System observability and resilience
• Multi-asset trading workflows

What We're Looking For

Essential:

• 5+ years of commercial C++ development experience
• Strong Linux systems programming background
• Experience building high-performance or latency-sensitive applications
• Deep understanding of networking and distributed systems
• Strong software design and architectural skills
• Experience owning production systems

Nice to Have:

• Go development experience
• Financial markets or trading technology experience
• FIX protocol knowledge
• AWS cloud experience

How You Work

We're looking for engineers who:

• Take ownership of what they build
• Deliver high-quality code into production
• Thrive in challenging technical environments
• Mentor and support others
• Communicate clearly in a distributed team
• Enjoy solving complex engineering problems
• Continuously improve systems, processes and people around them

What You'll Get

Competitive Benefits Package:

• 30 days annual leave + bank holidays
• Private medical insurance
• Pension scheme
• Life assurance
• Dental and optical cashback
• Cycle to Work scheme
• Team socials and company off-sites

Career Growth:

• Progression to lead roles, performance specialisation, or technical leadership. We invest in people who invest in us
• Exposure to cutting-edge trading technology.
• High levels of ownership and autonomy
• Opportunity to influence a platform used by some of the world's largest financial institutions

Remote-First Culture

We trust great engineers to do their best work wherever they are. Our remote-first approach prioritises flexibility, collaboration and sustainable working practices without sacrificing technical excellence.

Ready to Build at the Edge of What's Possible?

Join an award-winning engineering team solving some of the most demanding challenges in electronic trading.

Right to Work: Candidates must have the existing right to work in the UK. We are not currently able to offer visa sponsorship for this role.

Equal Opportunities: Reactive Markets is an equal opportunities employer. We welcome applications from all qualified candidates regardless of age, disability, gender reassignment, marriage or civil partnership, pregnancy or maternity, race, religion or belief, sex, or sexual orientation.

Reasonable Adjustments: If you need any adjustments or support during the application or interview process, please let us know — we're happy to accommodate.

Data Protection: By applying, you consent to Reactive Markets processing your personal data for recruitment purposes, in line with our privacy policy .

Apply now and help shape the next generation of high-performance trading infrastructure.

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