Senior Backend Software Engineer - Backend Systems in London

About the Role: As a Senior 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 build backend services in Go that power AI infrastructure, networking, inference orchestration, and model lifecycle management
• Implement secure, reliable APIs (gRPC/REST) and backend systems
• Design and develop Kubernetes Operators to manage compute and networking resources
• Contribute to architectural discussions, providing input on design reviews and system evolution
• Collaborate closely with platform and infrastructure teams to deliver production-grade, secure, and scalable services
• Maintain high standards for code quality, observability, and maintainability through reviews and best practices

What You Bring:

• Proven experience developing production systems in Golang
• Hands-on experience designing and deploying distributed systems and APIs (gRPC, REST) in production environments
• Solid understanding of Kubernetes internals (Scheduler, CNI, Operators, CSI, CAPI)
• Familiarity with CI/CD workflows, observability tooling, security, and automation best practices
• Collaborate across teams, contribute to architectural and development best practices
• A bias for ownership, accountability, and delivering high-quality software

Preferred Skills (Nice to Have):

• Infrastructure and networking knowledge
• Experience with Authentication, Authorization, RBAC and security best practices
• Nvidia hardware and software (GPU, Cumulus, NVLink)

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: 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 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

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.