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# Principal Software Engineer - Networking

- **Company:** Radiant
- **Location:** United Kingdom
- **Contract:** Permanent contract
- **Skills:** Application Programming Interfaces (APIs), Border Gateway Protocol, Computer Clusters, Configuration Management, Code Review, Computer Networks, Network Congestion, Software Design Documents, Ethernet, InfiniBand, Networking Hardware, Network Security, Network Control, Network Planning and Design, Routing, Remote Direct Memory Access, AI Infrastructure, Cloud Platform System, Build Management, Kubernetes, Open Network Automation Platform
- **Published:** November 11, 2026
- **Apply:** https://startup.jobs/principal-software-engineer-networking-radiant-10735848

## About the Role

* Extensive experience building and operating large-scale network software or software-driven networks.
 * 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 one or more systems languages such as Go or similar.
 * Deep technical expertise across:

 * Fabrics: RDMA, InfiniBand, RoCE, Ethernet at scale, congestion control
 * Networking: routing, switching, BGP, EVPN/VXLAN, overlays and underlays
 * Automation: network-as-code, configuration management, APIs for network devices
 * Multi-tenancy: isolation, segmentation, network security

 * Hands-on experience with technologies such as NVIDIA networking, SONiC, Cumulus, or similar.
 * Understanding of how network design affects AI training and inference performance.
 * Excellent written and verbal communication, including clear design documents and explaining complex trade-offs to technical and non-technical audiences.
 * Comfortable working directly with customers on highly technical problems.

## Description

As a Principal Software Engineer - Networking, you will help set the technical direction for Radiant's networking software, and lead the design and delivery of the systems that build, automate, and operate the fabric connecting our GPU clusters.

You'll work across high-performance cluster fabrics, network automation, Managed Networks, and multi-tenant isolation. You'll partner closely with product, infrastructure, SRE, storage, and security teams, and with customers whose workloads depend on the network., * Set the technical vision and architecture for Radiant's networking software, and lead its design and implementation.

 * Design and build the control plane that provisions, configures, and automates our cluster fabrics and Managed Networks.
 * Translate product and customer requirements into robust architectures, APIs, and technical designs, working closely with Product.
 * Own network performance, isolation, and reliability for AI training and inference workloads.
 * Lead integration of networking with compute, Kubernetes, storage, security, and observability.
 * Drive operational excellence with SRE and Infra Ops, including automation, monitoring, and incident response.
 * Raise the engineering bar across the organisation through mentoring, design and code review, and technical standards., * 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., * 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 Exercise * Final.