{"id":3988046,"url":"https://alion.io/job/radiant-principal-software-engineer-security","title":"Principal Software Engineer - Security","company":{"id":8822,"name":"Radiant","domain":"radiant.com","url":"https://alion.io/company/radiant","size_band":null,"is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":{"grade":"B","score":83,"open_postings":3,"ghost_share":0,"stale_share":0.667,"repost_share":0,"time_to_fill_p50_days":49,"computed_at":"2026-11-09T06:03:00Z"}},"role":"Backend","role_family":"Backend","seniority":"lead","employment_type":"full_time","work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["Gloucester, United Kingdom"],"countries":["GB"],"hiring_countries":[],"hiring_countries_total":0,"salary":null,"salary_estimate":null,"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"CI/CD","optional":false},{"name":"Go","optional":false},{"name":"IAM","optional":false},{"name":"ISO 27001","optional":false},{"name":"Kubernetes","optional":false},{"name":"Least Privilege","optional":false},{"name":"SIEM","optional":false},{"name":"Sigstore","optional":false},{"name":"SOC 2","optional":false},{"name":"Vault","optional":false},{"name":"Zero Trust","optional":false}],"status":"live","first_seen_at":"2026-11-09T19:33:24Z","employer_posted_date":"2026-11-09","last_verified_at":"2026-11-09T22:19:01Z","board_verified":true,"closed_at":null,"days_open":0,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":0},"description":"What You'll Do\nAs a Principal Software Engineer - Security, you will help set the technical direction for Radiant's security capabilities across the cloud platform and infrastructure, leading the design and delivery of the systems that underpin them.\nYou'll work across identity, access control, secrets, network security, platform hardening, auditability, and compliance controls. You'll partner closely with product, infrastructure, SRE, networking, security, and compliance teams, and with customers on their most demanding security requirements.\nThis is a hands-on technical leadership role focused on making security embedded, scalable, automated, and easy to consume across the platform, through architecture, code, and the standards other teams build on.\nKey Responsibilities\nSet the technical vision and architecture for security systems and platform capabilities, and lead their design and implementation.\n\nDesign and build core security services across IAM, RBAC, workload identity, secrets, encryption and key management, audit logging, network controls, and policy enforcement.\n\nTranslate product, customer, and regulatory requirements into robust architectures, APIs, and technical designs, working closely with the Security Product Manager.\n\nDrive automation of policy enforcement, configuration hardening, detection, remediation, and software supply chain security.\n\nEnsure strong tenant isolation and least-privilege access across the control plane and network and data plane.\n\nAct as a senior technical voice in enterprise customer security reviews, audits, and incident response.\n\nRaise the security engineering bar across the organisation through mentoring, code review, and technical standards.\n\nYour Profile\nStrong hands-on engineering skills in one or more systems languages such as Go or similar.\n\nExtensive experience building and operating large-scale distributed systems, with significant depth in cloud and network security, IAM, or security infrastructure.\n\nA track record of technical leadership at staff or principal level, including setting direction across multiple teams and delivering complex, high-stakes systems.\n\nDeep technical expertise across:\n\nIdentity & access: IAM, RBAC/ABAC, OAuth 2.0, OIDC, SAML, SSO, federation, mTLS, workload and service identity\n\nSecurity controls: applied cryptography, encryption at rest and in transit, secrets management, KMS/HSM, key rotation, policy engines\n\nInfrastructure: Kubernetes internals, containers and runtime isolation, cloud networking, compute, storage\n\nSecurity operations: audit logging pipelines, detection engineering, vulnerability management, incident response\n\nAutomation: policy-as-code, infrastructure-as-code, CI/CD security, software supply chain (signing, SBOMs, provenance)\n\nHands-on experience with technologies such as Vault, OPA/Gatekeeper, SPIFFE/SPIRE, Kubernetes admission control and security tooling, Sigstore, SIEM platforms, cloud KMS, or similar.\n\nDeep understanding of multi-tenancy, least privilege, zero-trust architecture, threat modelling, and shared-responsibility models.\n\nFamiliarity with compliance frameworks such as SOC 2 or ISO 27001, and how they translate into technical controls.\n\nAble to balance security, performance, reliability, operational complexity, and developer experience.\n\nExcellent written and verbal communication, including clear design documents and explaining complex trade-offs to technical and non-technical audiences.\n\nWhat You Bring\nSecurity mindset: Think like an attacker and design systems that fail safely, without making them painful to use.\n\nEngineering excellence: Write and review code that sets the standard for correctness, reliability, and maintainability.\n\nArchitectural judgement: Make sound long-term decisions on systems that are hard to change once built.\n\nTechnical leadership: Influence direction across teams without relying on authority, and grow the engineers around you.\n\nSystems thinking: Understand how controls interact across the full cloud platform, from network and infrastructure up to APIs and user experience.\n\nOwnership: Drive security capabilities from design through production, operation, and continuous improvement.\n\nQualities we look for:\nSet the standard: Every single day, you spot opportunities to constructively shake things up\n\nInspire the change: There's no blueprint for the future. You'll embrace challenges and change\n\nYou'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.\n\nWhy should you join us?\nWhat sets us apart is our blend of modern technology, competitive benefits, and an open, welcoming work culture that enables our people to thrive.\nHere are just some of the great things you can expect from us:\n25 days of annual leave\n\nA culture that emphasises results over hierarchy, process & ego: we place great emphasis on the quality, ingenuity and creativity of work.\n\nOpen 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.\n\nLearning Time: we all have dedicated learning time to focus on new skills, projects or interests that lay outside of your day-to-day job.\n\nHealth & Wellbeing: we want everyone to feel healthy and happy, so we offer private medical insurance via Bupa.\n\nCycle to Work Scheme: we're committed to building a sustainable business, so we encourage cycling to work.\n\nGympass subscription to a variety of gyms and wellbeing apps\n\nParticipation in the company shares program\n\nEnhanced parental pay & leave\n\nOur process: Talent screen → Hiring Manager → Technical interview (two Principal Engineers) → Whiteboard Session → Final.\nCompany Overview:\nRadiant is redefining how AI infrastructure is built.\nWe 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.\nWe are not building a generic cloud. We are building purpose-built AI infrastructure - from powered land, to compute, to software.\nAs 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. 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