Adoption & Ecosystem

Who uses it

The repository has no ADOPTERS file, so named adopters are limited to those with a citable public source. The one named in the CNCF graduation announcement is Giant Swarm.

Organisation	Use case	Source
Giant Swarm	Calls cert-manager an essential component of its Cluster API-based Kubernetes platform	source 3

Adoption signals

Beyond named adopters, the public signals are large. At graduation on 2024-11-12 the project and CNCF reported roughly 500 million downloads per month, that 86% of new production clusters install it by default, 450+ contributors, and 200+ releases (source 3, source 4).

On GitHub the cert-manager/cert-manager repository had 13,873 stars and 2,383 forks as observed on 2026-06-22 (source 1). It is a CNCF Graduated project (source 9).

Ecosystem

cert-manager is usually run alongside complementary tools rather than alone. trust-manager (same cert-manager org) distributes CA bundles, and external-secrets syncs secrets from external stores; both are commonly paired with it (source 5).

On the issuer side it integrates with Let's Encrypt and other ACME CAs, HashiCorp Vault PKI, Venafi and CyberArk, CyberArk Certificate Manager, EJBCA, and in-cluster or self-signed CAs, and it feeds certificates to Ingress controllers and the Gateway API (source 1, source 5). Commercially, CyberArk Certificate Manager for Kubernetes (formerly Venafi TLS Protect) builds discovery, policy, FIPS, and support on top of cert-manager, and Keyfactor reaches Kubernetes through a cert-manager issuer (source 5, source 6).

Alternatives

cert-manager is the de facto standard for in-cluster Kubernetes certificate automation (source 5). The real alternatives differ in philosophy rather than being drop-in replacements.

Alternative	Differs by
HashiCorp Vault PKI	Issues short-lived certificates on demand via API; on Kubernetes it is commonly used as a cert-manager backend rather than instead of it (source 5)
Venafi / Keyfactor (enterprise CLM)	Full certificate lifecycle management with per-identity pricing that scales poorly against ephemeral Kubernetes workloads, where cert-manager's open-source model is the OSS advantage (source 5)
CyberArk Certificate Manager for Kubernetes	A commercial layer on top of cert-manager adding discovery, policy, FIPS, and support, not a separate engine (source 6)