Principal SDET

What You'll Do

As a Principal SDET, you will help set the technical direction for testing and quality in one of our engineering teams. This is not traditional QA: you'll build the test infrastructure and developer experience that let the team ship quickly and safely.

You'll partner closely with software engineers, platform engineers, and SRE.

This is a hands-on technical leadership role, through architecture, code, and the standards other teams build on.

Our Engineering teams are grouped as follows:

• Infrastructure: Compute, Infra, Network & Storage.

• Platform: Cloud, Observability & Security.

• AI: Training & Inference.

Key Responsibilities

• Set the test strategy and architecture for your team.

• Build test frameworks for APIs, services, and end-to-end flows.

• Build test environments that reflect real GPU and cluster behaviour.

• Integrate testing into CI/CD so it's fast and reliable.

• Make testing easy for every engineer, and raise the quality bar across teams.

Your Profile

• Extensive software engineering experience, focused on testing and quality infrastructure.

• 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.

• Experience testing gRPC and REST APIs and distributed systems.

• Experience building end-to-end test frameworks and test environments.

• Excellent written and verbal communication, including clear design documents and explaining complex trade-offs to technical and non-technical audiences.

What You Bring

• Developer experience: Think in fast feedback for engineers, not just test coverage.

• 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.