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 $75 billion in daily trading volumes across FX, Equities, and Cryptocurrency, connecting 60+ 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