cert-manager vs Smallstep Certificate Manager

cert-manager is a free, open-source tool for obtaining and managing X.509 certificates on Kubernetes and OpenShift. It requests certificates from public or private issuers, keeps them valid, and attempts renewal before expiration. The project automates TLS certificate issuance for Kubernetes Ingress and supports private-PKI certificates for pod-to-pod mutual TLS. Documented authority options include Let’s Encrypt, HashiCorp Vault, CyberArk Certificate Manager, and private PKI. Installation can use kubectl-applied manifests, Helm, Flux, or Argo CD. Related projects include istio-csr, approver-policy, Kubernetes CSI drivers, csi-driver-spiffe, and trust-manager; trust-manager distributes X.509 trust bundles and can run independently. cert-manager publishes threat-model and hardening guidance covering secrets, RBAC, networking, and Kubernetes configuration. Its default Helm values prioritize installation ease and backward compatibility over hardened production security. The project has no LTS releases, though each release is supported until the second subsequent version.

Smallstep Certificate Manager has no write-up on Specifiction yet; its figures are above.