Principal Software Engineer: Cloud Platform in London

As a Principal Software Engineer at Radiant, you’ll be a hands‑on technical leader, driving the design and development of our most critical systems, including our GPU orchestration layer, inference‑serving infrastructure, and core platform APIs. You’ll set the standard for engineering excellence across the team, working closely with other principal engineers to align on strategy and drive technical leadership. You’ll partner with peers in infrastructure and machine learning to deliver high-performance AI systems, and mentor engineers across multiple squads. While you won’t have direct reports, you’ll play a pivotal role in shaping engineering direction, design decisions, and cross‑team collaboration.

What you’ll do:

• Design and develop core services for the Radiant AI Cloud Architect and build core backend services in Go that power AI infrastructure, networking, inference orchestration, and model lifecycle management.
• Lead engineering design efforts across the backend domain – architecture reviews and system evolution strategies.
• Collaborate closely with platform and infrastructure to deliver reliable, secure, production‑grade services.
• Drive technical standards and mentorship, upholding code quality, observability, and maintainability across teams.
• Proactively identify and resolve architectural bottlenecks, performance issues, or scaling challenges.

What you bring:

• Proven expertise in Golang and cloud‑native backend development.
• Deep experience designing and deploying distributed systems and APIs (gRPC, REST) in production environments.
• Strong knowledge of Kubernetes internals, with deep understanding of primitives, deployments, and reconciliation loops.
• Experience with PostgreSQL or equivalent high‑performance data stores.
• Experience with CI/CD workflows, observability, security, and automation best practices.
• Demonstrated ability to lead technically: mentor others, drive architectural thinking, and influence across teams.
• A bias for action, accountability, and leading by example.

Preferred skills (nice to have):

• Experience with AI/ML infrastructure tooling (e.g. vLLM, KServe, Ray, Triton).
• Familiarity with Python, especially ML libraries and model interfaces.
• Familiarity with GPU scheduling, inference pipelines, or resource‑constrained workload orchestration.
• Exposure to GPU orchestration frameworks or building services for model training/inference.
• Understanding of multi‑tenant systems, isolation strategies, and secure infrastructure for AI workloads.

How you work:

• You approach problems with a systems mindset – balancing practical execution with long‑term scalability.
• You elevate the team, setting high standards for technical quality and engineering excellence.
• You hold yourself and others accountable – giving direct feedback and expecting the same.
• You take initiative, owning challenges end to end and proactively driving solutions.
• You invest in others, mentoring to build both capability and confidence.
• You communicate clearly – translating complexity into clarity across engineering and business audiences.

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.

Benefits:

• 30 days of annual leave – we value your peace of mind. With 30 days off (excluding public holidays) and access to mental health resources, we make sure you’re as strong mentally as you are professionally.
• A culture that emphasizes 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 lie outside of your day‑to‑day job.
• Health & well‑being – 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 programme.
• Enhanced parental pay & leave.

Diversity, Equality, Inclusion and Belonging

We are an equal opportunity employer and we strive to reduce unconscious bias throughout our hiring process. All applicants will be considered for employment without attention to ethnicity, religion, sexual orientation, gender identity, family or parental status, national origin, veteran, neurodiversity status or disability status. To ensure our recruitment processes provide an equal opportunity for all applicants to succeed, we encourage you to let us know if there are any adjustments that we can make.