Senior Infrastructure Engineer

Remote (UK-based), with occasional on-site work at our data centres | Full-Time

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 50+ 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.

We’re looking for a Senior Infrastructure Engineer to help run and grow the network and cloud estate behind our trading platform. Networking in our colocation data centres is the core of the role. The estate spans London, New York and Singapore, and from Q1 2027 a new Tokyo data centre.

This is a hands-on role in a small, expert infrastructure team. You’ll work closely with our Head of Infrastructure, following problems from the cross-connect through hosts, containers and AWS. You’ll also help keep infrastructure delivery on track, from timelines and reporting to working closely with our TechOps team.

• Low-latency networking across our colocation sites: switching and routing, cross-connects, BGP peering with liquidity providers and clients, and the fabric that carries our trading traffic

• Bringing new sites to application-ready, starting with Tokyo

• Our hybrid connectivity into multi-region AWS, including Direct Connect, routing and failover

• Linux hosts and containers on the critical path, with every change made through code (Ansible, Git, Terraform), never by hand

• Monitoring and alerting that catches problems before clients do, plus runbooks and post-incident reviews that someone else can follow

• Planning and capacity: forecasting growth, setting timelines and reporting progress to TechOps and engineering

• 4+ years running production infrastructure in a latency-sensitive environment, such as HFT, an exchange, market data or bank trading infrastructure

• Strong networking: hands-on routing and switching (MLAG, LACP, VLANs), BGP in production, and a solid grasp of low-latency behaviour such as buffers, microbursts and congestion handling

• Colocation experience: cabinets, cross-connects, remote hands and vendor management

• Solid Linux (RHEL) and TCP/IP, and the ability to trace a problem from the wire to the application

• Infrastructure as code and containers as your default way of working

• Working knowledge of AWS networking, and the confidence to pick up the rest of our stack. Networking depth matters more to us than any particular cloud or platform tooling

• Methodical, evidence-led troubleshooting and clear documentation

A strong plus:

• Project management experience: owning timelines, reporting progress, and working with ops teams to hit deadlines

• Kernel bypass (Onload/ef_vi), PTP and time synchronisation

• Experience bringing up a new colo site

• FIX protocol or OTC FX market knowledge

• Python for tooling

Working pattern: Infrastructure changes are often scheduled outside trading hours, including weekends, and the team shares an on-call rota. We’re a team with flexible hours, so time worked out of hours is taken back during the week. Day-to-day work is remote, with occasional visits to our data centres, most often in London (Slough).