Principal Software Engineer - Engineering Applications

The Principal Software Engineer role at PhysicsX is an individual contributor role with leadership and collaboration expectations. The Principal is expected to be an effective technical thought-partner to non-technical stakeholders and to contribute strongly to an environment of growth and development in the craft of software engineering across the organisation.

What you will do

• Engage with product managers, designers, and users of Reference Applications to fully understand the what and why of the product’s functional requirements.
• Partner with the product leadership of Reference Applications to define the art of the possible with ambitious pragmatism, defining the how and when of product development.
• Take responsibility and accountability for the implementation of components and services by a team of software engineers, and actively participate in development by contributing to source-code, documentation, and CI/CD workflows.
• Design and maintain services that are fully interoperable with PhysicsX’s other platform services, while remaining independently versioned, tested, and deployed.
• Define, evolve, and advocate for a scalable, modular front-end architecture that enables reuse, rapid development, and long-term maintainability.
• Implement standardised instrumentation for metrics, logs, and traces and take responsibility for the teams’ prompt remediation of issues in production.
• Establish performance benchmarking to measure compliance with non-functional requirements, right-size infrastructure requests, and provide appropriate SLAs.
• Participate in establishing company-wide software engineering standards through engagement with the software engineering guild.
• Participate in the growth and development of software engineers.
• Participate in the recruitment and onboarding of software engineers.

What you bring to the table

• A passion for the evolving craft of software engineering and for sponsoring a culture of excellence in the craft.
• A proven ability to act as an effective technical thought-partner to non-technical stakeholders.
• A proven ability to lead teams of software engineers in a fast-paced and iterative environment, through active participation in problem solving, coaching, and architectural decision-making.
• A solid track-record of designing, building, and maintaining application services in distributed architectures.
• Strong experience deploying applications on Kubernetes, leading to a high level of independence in writing IaC (Helm, Terraform, Crossplane) and CI/CD workflows (GitHub Actions, ArgoCD), and a focus on designing applications that leverage native Kubernetes resources over CSP managed services.
• Experience with workflow orchestration, event-driven systems, and messaging (NATS, ArgoWorkflows).
• 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.
• Proficiency in TypeScript, React, and state management (Zustang, Jotai, Redux, MobX). Experience with TypeScript and React is expected, but your identity is not defined by them.
• Proficiency in Python and Go, with experience in other languages a plus (Rust, C++).
• A strong understanding of the machine learning development lifecycle.

Ideally

• Experience building rich, interactive visualisations using libraries such as Plotly, ECharts, Three.js, VTK, or WebGL to expose complex simulation data to end-users.
• Experience in the design and development of cloud based platforms requiring secure and isolated environments for the execution of arbitrary code.
• Experience in the design and development of configuration-driven developer tooling, particularly involving the dynamic generation of web applications through composition.
• Experience with the Nx build system.

What We Offer

• 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.

We value diversity and are committed to equal employment opportunity regardless of sex, race, religion, ethnicity, nationality, disability, age, sexual orientation or gender identity. We strongly encourage individuals from groups traditionally underrepresented in tech to apply. To help make a change, we sponsor bright women from disadvantaged backgrounds through their university degrees in science and mathematics.

We collect diversity and inclusion data solely for the purpose of monitoring the effectiveness of our equal opportunities policies and ensuring compliance with UK employment and equality legislation. This information is confidential, used only in aggregate form, and will not influence the outcome of your application.