Devops Engineer in Harrow on the Hill

Location: London; full in-office working as default

Start date: ASAP

Reports to: CTO

Compensation: £60 - 90k + Equity

At Cosine, we’re building autonomous AI engineers that plan, write, and ship code inside real development workflows. Cosine is designed for on-premise and virtual private cloud (VPC) deployments, including fully air-gapped environments. We build our agent tooling entirely in-house and post-train open-source models to deliver reliable, enterprise-grade coding performance in security-critical settings.

This role is based in our Hoxton office, five days a week, because close collaboration, fast feedback, and shared context matter for the problems we’re solving.

We’re looking for a Devops / Senior Platform / Infra Engineer to own the core infrastructure that powers Cosine’s products — from Kubernetes and deployment pipelines to networking and platform services.

You’ll design and run the “paved road” that our engineers, researchers, and customers build on: reliable Kubernetes clusters, fast and safe CI/CD, solid observability, and hardened environments for demanding enterprise and on-prem deployments. You’ll also wear a classic “DevOps/SRE” hat: thinking in SLOs, running incident response, and keeping us up even as we move quickly.

This is a high-ownership role at a fast-paced, venture-backed Silicon Valley startup. You’ll work directly with founding engineers and leadership, and your decisions will materially shape how we build and ship products.

• Own core infrastructure
• Design, operate, and evolve our Kubernetes-based platform (EKS or similar), including cluster topology, node groups, autoscaling, and multi-environment isolation.
• Manage supporting cloud resources: container registries, load balancers, queues, caches, and data infra needed to run our APIs and agents.
• Build the deployment & tooling layer
• Design and maintain CI/CD pipelines for image builds and infra rollouts (e.g. Pulumi/Terraform + Helm/Docker).
• Implement safe rollout strategies (blue/green, canary, staged rollouts) and fast rollback paths.
• Build internal tools and abstractions that make it easy for product teams to self-serve infra safely.
• Own reliability & operations (SRE-ish)
• Define and track SLOs/SLIs for key services (latency, error rates, availability).
• Improve our observability stack (metrics, logs, traces, alerts) so issues are obvious, actionable, and debuggable.
• Participate in the on-call rotation, lead incident response when needed, and drive blameless post-mortems and fixes.
• Shape networking & security
• Design and maintain networking: VPCs, subnets, ingress/egress, service meshes / L7 routing, DNS, and TLS.
• Implement least-privilege access via IAM, secure secret management, and hardened configurations for multi-tenant and isolated customer environments.
• Help design patterns for secure enterprise and on-prem / regulated deployments.
• Partner with product & research
• Work closely with application, ML, and research teams to understand their needs and translate them into reusable infra building blocks.
• Provide guidance on “how to run this in production” — capacity planning, failure modes, and operational readiness reviews.

• 5+ years building and operating production infrastructure on a major cloud (AWS, GCP, or Azure).
• Significant hands-on experience running Kubernetes in production (EKS/GKE/AKS or self-managed): Cluster upgrades, autoscaling, node group design, and multi-env setups.
• Deep experience with IaC tools (Pulumi, Terraform, CDK, or similar).
• Have owned the uptime and performance of user-facing systems.
• Comfortable participating in (and improving) on-call rotations and incident management.
• Experience setting up / tuning observability (Prometheus, Grafana, CloudWatch, OpenTelemetry, etc.).
• You’ve built internal tools, libraries, or platforms on top of cloud providers so product teams can move faster with fewer foot-guns.
• Strong scripting and programming skills in at least one modern language (e.g. TypeScript, Go, Python).
• Enjoy working in a fast-moving environment with evolving priorities and incomplete specs.
• Communicate clearly, give/receive direct feedback, and collaborate across functions.

• Experience with AWS primitives like EKS, ECS/Fargate, ECR, SQS, ElastiCache/Redis.
• Argo CD or other GitOps tools for Kubernetes.
• On-prem, air-gapped, or regulated industry deployments (e.g. finance, healthcare).
• AI/ML infrastructure (GPU workloads, model hosting, feature stores).
• Prior experience as an early infra / platform hire at a startup.

Cosine is an equal opportunity employer. We value diverse backgrounds, perspectives, and ways of thinking, and we’re committed to creating an inclusive and respectful workplace. We encourage applications from anyone who meets the role requirements, even if you don’t meet every single qualification. If you need reasonable adjustments at any stage of the hiring process, we’re happy to discuss them.

We’re an in-office team, five days a week, by design. We believe the work we’re doing benefits from being together, collaborating closely, and building shared context.

What You Can Expect

• Competitive salary, benchmarked to the market
• Equity / share options, so you share in the upside you help create
• 30 days’ holiday +