Senior Software Engineer - Core Services in London

About us PhysicsX is a deep-tech company with roots in numerical physics and Formula One, dedicated to accelerating hardware innovation at the speed of software. We are building an AI-driven simulation software stack for engineering and manufacturing across advanced industries. By enabling high-fidelity, multi-physics simulation through AI inference across the entire engineering lifecycle, PhysicsX unlocks new levels of optimization and automation in design, manufacturing, and operations — empowering engineers to push the boundaries of possibility. Our customers include leading innovators in Aerospace, Materials, Energy, Semiconductors, and Automotive.

The Role PhysicsX is building a platform that enables Data Scientists and Simulation Engineers to build, train, and deploy Deep Physics Models. Our platform serves multiple tenants across highly regulated industries, making robust identity, access control, and operational visibility foundational to everything we do. We're looking for a Senior Software Engineer to join our Core Services team, the team building the foundational primitives that give our customers superpowers they've never had before. For decades, engineers have been trapped using siloed, rigid tools from the 90s. We're changing that by enabling secure, permissioned collaboration at the frontier of AI. You'll design and build the enterprise-grade systems that make this possible. From fine-grained permissions to instrumentation, you'll create the primitives that every product across PhysicsX adopts, ensuring every user, service, and agentic workflow is securely identified, correctly scoped, and fully observable. You'll own the infrastructure that keeps our platform trustworthy, transparent, and ready for the future of manufacturing and engineering.

What You Will Do:

• Design and implement authentication and authorisation systems, including identity provider integrations, token management, session handling, and SSO flows.
• Architect and build fine-grained role-based and attribute-based access control (RBAC/ABAC) models that scale across multi-tenant environments.
• Own the platform's permissions layer end-to-end: from policy definition and enforcement through auditing and compliance reporting.
• Build and maintain telemetry infrastructure distributed tracing, structured logging, metrics collection, and alerting, to provide deep observability across services and environments.
• Define and enforce security standards across APIs and services, including schema governance, data segregation, and least-privilege access patterns.
• Design and implement identity and access patterns for AI agents, including MCP authentication, agent impersonation flows, and system account models that allow agents to act securely on behalf of users in a regulated, multi-tenant environment.
• Contribute to the design of multi-service architectures, ensuring authentication and authorisation concerns are cleanly integrated and consistently enforced across both human and agentic workflows.
• 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 reviews to evaluate and adopt new tools and approaches.
• Mentor junior and mid-level engineers, facilitate technical discussions, and build consensus around architectural decisions.

What you bring to the table:

• A passion for the craft, you're driven by engineering excellence and committed to fostering that culture across the team.
• Strong software engineering foundations, solid grasp of algorithms, data structures, and system design.
• You write clean, maintainable, testable code and have strong command of Golang and Python.
• Authentication and identity expertise, hands-on experience building or integrating identity and access management systems (e.g., Keycloak, Auth0, Okta).
• Deep understanding of OAuth 2.0, OIDC, SAML, and token-based authentication flows.
• Ability to effectively leverage cloud provider IAM systems (e.g., AWS IAM, GCP IAM, Azure AD).
• Authorisation and permissions design, proven experience implementing RBAC, ABAC, or policy-as-code frameworks (e.g., OPA/Rego, Cedar) in production multi-tenant systems.
• Telemetry and observability, experience designing and operating metrics, tracing, and logging pipelines (e.g., OpenTelemetry, Prometheus, Grafana, Jaeger).
• You understand what it takes to make distributed systems genuinely observable.
• Kubernetes and GitOps, strong working knowledge of Kubernetes and ArgoCD, including deploying, managing, and troubleshooting services in production clusters.
• API and service design maturity, experience designing multi-service systems with attention to schema governance, forward compatibility, and secure data access patterns.
• Proven ability to develop schema drift mitigation strategies with minimal impact to dependent clients (e.g., forward-compatible schemas, ACLs, ambassador sidecars).
• Agent governance awareness, understanding of how identity and permissions extend to agentic systems, including MCP auth, impersonation, system accounts, and scoped token delegation.
• Security awareness, familiarity with threat modelling, secure coding practices, and participating in security testing and compliance workflows.
• CI/CD and deployment expertise, hands-on experience building and optimising CI/CD pipelines, including multi-service and zero-downtime deployments across numerous customer environments.
• Communication and collaboration, excellent communication skills to work across teams, understand requirements from research scientists and product stakeholders, and translate them into technical specifications.
• AI-native mindset, you follow the frontier of agentic systems and AI tooling.
• You naturally think about how infrastructure needs to evolve when agents, not just humans, are the consumers of your APIs and services.
• You actively use AI coding tools (e.g., Copilot, Cursor, Claude Code) in your daily workflow and see them as a force multiplier, not a novelty.
• Incremental mindset, you work in small steps toward larger goals, driving change through continuous improvement rather than massive redesigns.
• You can zoom in on details and zoom out to see the big picture.

Ideally:

• Polyglot programming, deep expertise in Python and Golang, with exposure to other languages such as Rust or C++.
• Advanced Kubernetes, ability to leverage resources that extend the Kubernetes API (e.g., CRDs, Operators) and infrastructure configuration tools (Crossplane, Helm charts).
• Infrastructure flexibility, understanding of what it takes to build software that runs in cloud, on-premises, and air-gapped environments.
• Advanced testing, experience with fuzzing, deterministic simulation testing, or fault injection in production systems.

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.
• 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.
• Influence over hierarchy - We operate with a flat structure: good ideas win - wherever they come from.
• Sustainable pace, long-term ambition - Building meaningful technology is a marathon, not a sprint.
• 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.