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Cybersecurity · head to head

authentik vs Cosign

authentik logo

authentik

Cybersecurity

Open-source identity provider with flexible authentication flows

From
Free
Rated
-
Full reviewWebsite
Cosign logo

Cosign

Cybersecurity

Signs and verifies container images and artifacts, with or without managing keys

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: authentik smaller project than Keycloak, with a correspondingly smaller community and fewer integration guides; Cosign keyless signing inherits every weakness of the identity provider behind it. Sigstore’s own threat model states that if an identity provider is compromised, Sigstore will issue certificates to those identities, so a compromised account produces perfectly valid signatures.
  • They diverge on capability: authentik covers Configurable flows, Cosign covers Keyless signing.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which authentik and Cosign actually diverge.

Attributes where authentik and Cosign differ
AttributeauthentikCosign
Pricing modelOpen-source core with a paid enterprise tierOpen source, no licence fee
PlatformsDocker, Kubernetes, Linux, Self-hostedmacOS, Linux, Windows, Docker

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Cybersecurity).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in authentik

  • Configurable flows
  • Protocol support
  • Application proxy
  • Modern admin interface

Only in Cosign

  • Keyless signing
  • Key and KMS signing
  • Registry-native storage
  • In-toto attestations
  • Offline verification
  • Trusted root and signing config

What people use each for

The jobs each tool is most often brought in to do.

authentik

  • Self-hosted SSO across internal services without commercial identity pricingnot Cosign
  • Putting authentication in front of applications that have none, via the proxynot Cosign
  • Teams who tried Keycloak and wanted something less heavynot Cosign

Cosign

  • Signing container images in a build pipeline without managing long-lived private keysnot authentik
  • Attaching a signed bill of materials to a release so consumers can verify its provenancenot authentik
  • Meeting a customer or regulatory requirement for signed artifactsnot authentik
  • Verifying third-party images before they enter an internal registrynot authentik

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

authentik

  • Smaller project than Keycloak, with a correspondingly smaller community and fewer integration guides
  • The flow model is flexible but conceptually unfamiliar, and simple setups can feel over-abstracted
  • Enterprise support and some governance features sit behind the paid tier
  • Self-hosted identity is still yours to secure, patch and keep available

Cosign

  • Keyless signing inherits every weakness of the identity provider behind it. Sigstore’s own threat model states that if an identity provider is compromised, Sigstore will issue certificates to those identities, so a compromised account produces perfectly valid signatures.
  • A signature proves who signed, never whether they should have. The documentation is explicit that Sigstore cannot determine authorisation, so every consumer must write and maintain their own identity and issuer policy or verification means nothing.
  • Nothing is enforced without an admission controller. Signing changes what you can prove, not what runs, and the official policy controller has a small maintainer base for a component sitting in a cluster admission path.
  • Upgrades break pipelines. Version 3 changed defaults, version 4 is announced as removing legacy functionality and roughly half the command line flags, and two official client libraries still lacked support for the new log format as of mid 2026.
  • Signatures do not expire. An artifact signed before a maintainer account was compromised and one signed after are indistinguishable unless somebody is actively monitoring the transparency log, and almost nobody is.

Pricing, plan by plan

authentik

Free
  • Open sourceFree
    • Full identity provider
    • All protocols
    • Community support

Cosign

Free
  • CosignFree
    • Apache-2.0
    • Public Sigstore infrastructure free to use
    • No usage limits published

Which should you pick?

Choose authentik if

  • You need configurable flows.
  • You want to start without paying.
  • You work on Docker, Kubernetes, Linux, Self-hosted.
  • You also want protocol support.
authentik review

Choose Cosign if

  • You need keyless signing.
  • You want to start without paying.
  • You work on macOS, Linux, Windows, Docker.
  • You also want key and kms signing.
Cosign review

Questions people ask

Is authentik or Cosign better?
Neither clearly leads. authentik starts at Free and Cosign at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, authentik or Cosign?
authentik starts at Free and Cosign at Free.
Does authentik or Cosign run on more platforms?
authentik runs on Docker, Kubernetes, Linux, Self-hosted. Cosign runs on macOS, Linux, Windows, Docker.
Can I use authentik for free?
Both have a free tier, so you can try either at no cost before committing.
What is authentik best used for?
authentik is most often used for self-hosted sso across internal services without commercial identity pricing, putting authentication in front of applications that have none, via the proxy, teams who tried keycloak and wanted something less heavy. Of those, self-hosted sso across internal services without commercial identity pricing and putting authentication in front of applications that have none, via the proxy are not what Cosign is typically brought in for.
What can authentik do that Cosign cannot?
authentik covers Configurable flows, Protocol support, Application proxy, Modern admin interface. Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations.

Answered from the vendors’ own pages

authentik: Is authentik free?

The open-source edition is free and complete for most use. An enterprise tier adds support and additional features.

Cosign: Does Cosign tell me if an image is vulnerable?

No. It has no vulnerability knowledge whatsoever. It can carry an SBOM as a signed attestation but never reads it. Pair it with a scanner.

authentik: authentik or Keycloak?

authentik is generally reported as easier to run and administer; Keycloak is more established with a larger community and Red Hat behind it.

Cosign: Is signing alone enough?

No. Verification is a command somebody runs. Without an admission controller enforcing it, an unsigned image still runs.

authentik: Can authentik protect apps with no login of their own?

Yes. Its application proxy places authentication in front of services that have no built-in authentication.

Cosign: What does a bare cosign verify actually prove?

Very little. Without a pinned certificate identity and OIDC issuer, it accepts a valid signature from any identity at all.

Cosign: What is the risk of keyless signing?

Your OIDC provider becomes the root of trust. Compromise of that account yields genuine, verifiable signatures, so account security is the control that matters.

Cosign: Should we expect breaking changes?

Yes. Version 4 is announced to remove roughly half the flags, and a post-quantum migration is named as a further breaking change after that.

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