Senior Frontend Engineer

Remote (UK-based) | Full-Time

About Us

Reactive Markets is the 2026 OTC Trading Platform of the Year (). 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 senior full-stack engineer to build the trading platform our clients use every day. Despite the "frontend" name, this is not a UI-only role — our Frontend team works across the whole application stack in TypeScript and Rust, from the trader-facing interfaces down to the services behind them. It's distinct from our Backend team, who own the low-latency C++/Go trading engine.

This is a senior individual contributor role for someone who takes on the hardest problems and delivers them under their own steam. You'll own complex, ambiguous, performance-critical work end-to-end — designed, built, tested, deployed, and supported in production. You lead through code, craft, and mentoring, setting the technical example the rest of the team calibrates to. This is not a role where you write code and throw it over a wall: our engineers own the full lifecycle, and when something breaks, 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

• Complex full-stack features in TypeScript and Rust — from trader-facing interfaces to the application services behind them

• Real-time market-data presentation and high-throughput, low-latency application code across FX, Equities, and Cryptocurrency

• React and reactive state management (RX, MobX, or similar) for demanding, data-dense trading interfaces

• Distributed systems and real-time data over REST, WebSockets, and network protocols

• Architecture and solution design for the hardest technical problems the team faces

• Observability and monitoring — dashboards, alerting, and metrics that make frontend behaviour visible

• Production systems that handle real money — reliability is not optional

What We Need

Technical:

• Strong full-stack engineering ability with deep TypeScript / JavaScript (ES6+) (5+ years)

• Solid experience with React and reactive state management (RX, MobX, or similar)

• Working knowledge of Rust, or the clear appetite and ability to get there — it's part of our stack

• Strong grasp of distributed systems, API design, and real-time data (REST, WebSockets, network protocols such as TCP/UDP and binary protocols)

• Comfortable reasoning about architecture and making defensible technical trade-offs

• Python for scripting, automation, and tooling is a bonus

• Git and Linux fundamentals

• 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 run with things. Give you an ambiguous, complex problem and you drive it to done without being managed through it. Senior here means trusted, not just experienced

• You have range. You're not just strong in the familiar parts of the stack — you pick up the unfamiliar and hold your own on the hardest work

• 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 raise the bar. You review peers' work thoughtfully, mentor the engineers around you through the craft, and set a standard others calibrate to

• 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 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 + 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.

Our Hiring Process

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

Stage 1: Initial Conversation with Talent Acquisition
Format: Video call, ~30-45 minutes

Stage 2: Hiring Manager Conversation with the relevant team lead or hiring manager
Format: Video call, ~60 minutes

Stage 3: Technical Interview with two members of the relevant engineering team
Format: Video call, interactive session, ~60 minutes

What to expect in each stage will be explained by Talent Acquisition if you're invited to interview. Throughout the process, we aim to keep momentum with no unnecessary delays between stages, and feedback typically comes within a few business days.

*Please note that depending on availability, Stage 2 and 3 may swap around.

How to Apply

Please apply directly via this job posting — all applications, including those submitted via LinkedIn, are managed through our applicant tracking system, so you'll always land in the same place regardless of where you found this role.

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.

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