Helmfile
Declarative wrapper for Helm — define all releases in one YAML file, apply atomically. Roboll, 2017. Pitch: what docker-compose is to Docker, helmfile is to Helm.
Handles: multiple environments (dev/staging/prod), per-environment values, release ordering (deploy DB before app), templating with Go templates or Jsonnet. helmfile apply is an idempotent sync of all releases. Competitors: ArgoCD ApplicationSet (more GitOps focus), Flux HelmRelease (same GitOps focus), Terraform with Helm provider. Often lives alongside GitOps flow — helmfile + Atlantis or helmfile-render → Kustomize → ArgoCD.