Buffer seeks a Senior Infrastructure Engineer to join a small infra team and own reliability and modernization of the production platform. Responsibilities include operating EKS/Kubernetes, ArgoCD/Argo Rollouts, Terraform-managed cloud resources, CI/CD and GitOps pipelines, observability (Datadog, Sentry), developer tooling (per-PR environments, CLIs), incident response, and using AI to reduce operational toil. Role is remote-first (preference for overlap with EMEA), includes distributed on-call shifts, and occasional in-person team travel once or twice per year.