Principal Platform Engineer

What You'll Do

As a Principal Platform Engineer, you will help set the technical direction for the platform one of our engineering teams builds on: the infrastructure, tooling, and automation that let us run GPU clusters, Kubernetes, and our managed services reliably at scale.

You'll partner closely with software engineers, SRE, Infra Ops, and the other platform engineers across Radiant.

This is a hands-on technical leadership role focused on making the platform reliable, secure, and easy to build on, through architecture, code, and the standards other teams build on.

The teams

• Infra: the platform behind provisioning and cluster management
• Network: the platform behind our fabrics and Managed Networks
• Cloud: the platform behind our Virtual Machines and console
• Observability: the platform behind FlightDeck
• MLOps: the platform behind training and inference

Key Responsibilities

• Set the platform architecture and roadmap for your team, and lead its design and implementation.
• Lead infrastructure-as-code, automation, and deployment at scale.
• Make environments reproducible, secure, and fast to change.
• Own the reliability and operability of the platform, with SRE and Infra Ops.
• Define standards for CI/CD, observability, and configuration across teams.
• Raise the engineering bar through mentoring, design and code review, and technical standards.

Your Profile

• Extensive experience in platform, infrastructure, or SRE engineering at scale.
• A track record of technical leadership at staff or principal level, including setting direction across multiple teams and delivering complex, high-stakes systems.
• Strong hands-on engineering skills in Go, Python, or similar.
• Deep technical expertise across:

• Kubernetes and containers in production, including operators
• Infrastructure-as-code and configuration management (e.g. Terraform, Ansible)
• CI/CD, release engineering, and GitOps
• Linux, networking, and cloud or bare-metal infrastructure

• Experience with GPU, HPC, or bare-metal platforms is a strong plus.
• Excellent written and verbal communication, including clear design documents and explaining complex trade-offs to technical and non-technical audiences.

What You Bring

• Platform thinking: Build the foundations other engineers rely on, and make them easy to use.
• Engineering excellence: Write and review code that sets the standard for correctness, performance, and maintainability.
• Architectural judgement: Make sound long-term decisions on systems that are hard to change once built.
• Technical leadership: Influence direction across teams without relying on authority, and grow the engineers around you.
• Systems thinking: Understand how your area interacts with compute, networking, storage, and the rest of the cloud platform.
• Ownership: Drive capabilities from design through production, operation, and continuous improvement.

Qualities we look for:

• Set the standard: Every single day, you spot opportunities to constructively shake things up
• Inspire the change: There's no blueprint for the future. You'll embrace challenges and change
• You're real and you're true to yourself: We cherish and celebrate diversity so you'll feel right at home whoever you are and whoever you're talking to, you treat everyone the same.

Why should you join us?

What sets us apart is our blend of modern technology, competitive benefits, and an open, welcoming work culture that enables our people to thrive.

Here are just some of the great things you can expect from us:

• 25 days of annual leave
• A culture that emphasises results over hierarchy, process & ego: we place great emphasis on the quality, ingenuity and creativity of work.
• Open communication, regular feedback: we value smooth collaboration, direct and actionable feedback, and believe that leading with empathy and a growth mindset makes us better together.
• Learning Time: we all have dedicated learning time to focus on new skills, projects or interests that lay outside of your day-to-day job.
• Health & Wellbeing: we want everyone to feel healthy and happy, so we offer private medical insurance via Bupa.
• Cycle to Work Scheme: we're committed to building a sustainable business, so we encourage cycling to work.
• Gympass subscription to a variety of gyms and wellbeing apps
• Participation in the company shares program
• Enhanced parental pay & leave

Our process: Talent screen → Hiring Manager → Technical interview (two Principal Engineers) → Whiteboard → Session Final.

Company Overview:

Radiant is redefining how AI infrastructure is built.

We design and operate AI-native cloud platforms engineered for sovereignty, performance, and scale. Our infrastructure powers GPU-native workloads, multi-tenant control planes, and high-performance AI systems designed for the most demanding environments.

We are not building a generic cloud. We are building purpose-built AI infrastructure — from powered land, to compute, to software.

As we scale, we're building this organisation from the ground up. We're looking for people who'd rather build the playbook than inherit one — who are comfortable doing the work themselves as well as directing others, and who can adapt as fast as our strategy does. This is a startup model: attitude and adaptability matter more to us than years of experience or the size of the team you've previously managed.