Senior Frontend Software Engineer

The Role

PhysicsX is developing a platform used by Data Scientists and Simulation Engineers to build, train, and deploy Deep Physics Models. The core of this platform relies on handling massive volumes of complex simulation data, enabling high-fidelity multi-physics simulation through AI inference.

We are looking for a Senior Frontend Software Engineer to join our product team. You will be one of a small team of Front-end Engineers, collaborating in a cross-functional team with autonomy to drive implementation decisions. You will build and evolve the frontend that brings our platform to life — from rich 3D visualisations of simulation data to seamless API integrations powering complex ML workflows. You will design composable frontend architectures, optimise performance for data-heavy interfaces, and ensure our engineers and scientists can interact intuitively with massive datasets and simulation results.

As a senior engineer, you will also play a key role in shaping technical direction — authoring Technical Decision Records, mentoring less experienced engineers, and driving the standards that keep our platform reliable, secure, and performant. This is a role for a builder who loves crafting exceptional user experiences as much as they love designing robust frontend architectures.

What You Will Do

• Build and evolve a frontend platform that supports complex simulation and ML workflows — from 3D visualisations to seamless API integrations and data-heavy interfaces.
• Design and implement composable frontend architectures and component systems, including micro-frontend patterns, to enable scalable and maintainable development.
• Optimise user experience through advanced caching strategies, performance monitoring, layout and paint optimisation, and accessibility best practices.
• Design and implement advanced state management and data flow patterns to handle the demands of real-time simulation data and complex user interactions.
• Own your work end-to-end — from architectural design through to deployment and maintenance in a fast-paced, agile environment.
• Define performance standards and SLAs for the services you own; diagnose and resolve complex performance bottlenecks in rendering, layout, and data handling.
• Collaborate with backend engineers on the implementation of security risk mitigation strategies and performance optimisations for frontend applications.
• Drive best practices in CI/CD, automated testing, observability, and infrastructure-as-code; build and maintain deployment pipelines including zero-downtime and multi-service deployments.
• Author and review Technical Decision Records; participate in Technology Radar reviews to evaluate and adopt new tools and approaches.
• Mentor junior engineers, facilitate technical discussions, build consensus around decisions, and translate research needs into well-defined technical requirements.

What You Bring to the Table

• A passion for the craft — a drive for engineering excellence and a commitment to sponsoring that culture across the team.
• Strong software engineering foundations — algorithms, data structures, and system design, with a passion for writing clean, maintainable, and testable code. You are a frontend engineer, not a framework developer — you understand the web platform deeply (HTML, CSS, JavaScript, browser APIs) and can build excellent interfaces regardless of the tech stack.
• Architectural versatility — proven track record building web-based user interfaces using a variety of architectural approaches — SPAs, server-rendered applications, hybrid architectures, micro-frontends — with a critical perspective on when each is the right choice. Experience with React and TypeScript is expected, but your identity is not defined by them.
• Web platform depth — strong understanding of how browsers work: rendering pipelines, layout and paint, networking, caching, the JavaScript event loop, and Web APIs. You optimise from first principles, not from framework-specific recipes.
• API and data handling maturity — experience designing frontends that integrate with complex backends via REST, GraphQL, WebSockets, and SSE, with attention to caching strategies, data access patterns, and forward compatibility.
• Reliability and observability mindset — experience defining performance standards and SLAs, implementing monitoring/alerting, and optimising observability in production environments.
• Security and accessibility awareness — familiarity with OAuth/JWT, XSS/CSRF prevention, WCAG, and ARIA standards; experience collaborating with backend teams on security risk mitigation.
• CI/CD and deployment expertise — hands-on experience building and optimising CI/CD pipelines (e.g. NX, GitHub Actions, monorepos), including multi-service and zero-downtime deployment strategies.
• Data visualisation experience — building rich, interactive visualisations using libraries such as Plotly, ECharts, Three.js, VTK, or WebGL to expose complex simulation data to end-users.
• Diagnostic and optimisation skills — a proactive mindset with the ability to identify and resolve complex performance bottlenecks from first principles — in rendering, networking, and data processing — rather than relying on framework-level fixes.
• Communication and leadership — excellent communication skills to discuss data needs with research scientists and translate them into technical specifications. Experience mentoring engineers and facilitating technical decisions.

Ideally

• Polyglot Frontend Thinking: comfort working beyond the JavaScript ecosystem — whether that means WebAssembly, compiled-to-JS languages, or non-SPA architectures. Willingness to reach for the right tool rather than the familiar one.
• 3D and GPU Technologies: deep experience with WebGL, WebGPU, or WebAssembly for high-performance rendering of simulation data, meshes, and point clouds.
• Design Sensibility: understanding of the limitations and trade-offs of design, layout, and typography constraints in the browser, with the ability to work with designers to reach a middle ground.
• Advanced Testing Techniques: experience with fuzzing, deterministic simulation testing, or fault injection in production systems; strong foundation in E2E and integration testing across different architectural patterns.
• Domain Knowledge: understanding of 3D geometry processing (meshes, point clouds) and the specific data structures used in physics-based simulations.

What we offer

Build what actually matters

Help shape an AI-native engineering company at a formative stage, tackling problems that genuinely matter for industry and society. This is work with real-world impact - and something you can be proud to stand behind.

Learn alongside exceptional people

Work with a high-caliber, collaborative team of engineers, scientists, and operators who care deeply about doing great work, and about helping each other get better. We come from diverse backgrounds, but we share a commitment to operating at the highest level and addressing some of the most complex challenges out there. If you’re ambitious, thoughtful, and driven by impact, you’ll feel at home.

Influence over hierarchy

We operate with a flat structure: good ideas win - wherever they come from. Questioning assumptions and challenging the status quo isn’t just welcomed, it’s expected.

Sustainable pace, long-term ambition

Building meaningful technology is a marathon, not a sprint. We believe in balancing focused, ambitious work with a life beyond it. Our hybrid model blends time together in our Shoreditch office with work-from-home days, giving you the flexibility to work sustainably while staying connected in person.

And it doesn’t stop there …

🚀 Equity options - share meaningfully in the company you’re helping to build.

🏦 10% employer pension contribution - because investing in future matters.

🍽️ Free office lunches - to keep you energised and focused.

👶 Enhanced parental leave - 3 months full pay paternity and 6 months full pay maternity leave, to provide extra flexibility during the moments that matter most.

🍼 YellowNest nursery scheme - to help working parents manage childcare costs.

☀️ 25 days of Annual Leave (+ Public Holidays)- because taking time to rest matters.

🏥 Private medical insurance - 100% employee cover, giving you complete peace of mind.

💪 Wellhub Subscription- gain access to thousands of gyms, classes and wellness apps, supporting both physical and mental wellbeing.

👀 Eye tests - because good work depends on good health.

📈 Personal development - dedicated support for learning, development, and leveling up over time.

💛 Employee Assistance Programme (EAP) - confidential wellbeing support, available whenever you need it.

🚲 Bike2Work scheme and🚆 Season ticket loan - to make getting to work easier and greener.

🚗 Octopus EV salary sacrifice - for a simpler, more sustainable way to drive electric.

🔎 Watch this space, we’re continuing to build this as we grow…