C++ Software Engineer
Remote (UK-based) | Full-Time
About Us
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.
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 Role
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.
What You'll Work On
-
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
What We Need
Technical:
-
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
What You Get
-
Real problems — trading systems where performance is measured in microseconds, not user clicks
-
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 +
Remote C++ Software Engineer in Chelmsford employer: Reactive Markets
Reactive Markets is an exceptional employer that fosters a dynamic work culture, prioritising innovation and collaboration. With a strong emphasis on employee growth, you will have access to continuous learning opportunities while working closely with a senior engineering team in a hybrid London setting. The company's commitment to outstanding client service and automation ensures that you will be part of a forward-thinking environment that values your contributions.
