Cybersecurity · head to head
Clerk vs Cosign
Clerk
Cybersecurity
Drop-in user authentication and management for developers
- From
- Free
- Rated
- -
Cosign
Cybersecurity
Signs and verifies container images and artifacts, with or without managing keys
- From
- Free
- Rated
- -
The short version
- Each has a real cost: Clerk pricing scales with monthly retained users, which can grow expensive quickly for consumer apps with large user bases.; 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: Clerk covers Prebuilt UI components, Cosign covers Keyless signing.
- Prices and features above were last checked on 31 August 2026.
Where they differ
Only the attributes on which Clerk and Cosign actually diverge.
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 Clerk
- Prebuilt UI components
- Organization management
- Multi-factor authentication
- Social sign-on
- Billing
- Enterprise connections
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.
Clerk
- Adding sign-in and user profiles to a web or mobile app quicklynot Cosign
- B2B SaaS apps needing organizations and role-based accessnot Cosign
- Startups wanting prebuilt UI instead of building auth in-housenot Cosign
- Apps needing MFA and fraud detection out of the boxnot Cosign
Cosign
- Signing container images in a build pipeline without managing long-lived private keysnot Clerk
- Attaching a signed bill of materials to a release so consumers can verify its provenancenot Clerk
- Meeting a customer or regulatory requirement for signed artifactsnot Clerk
- Verifying third-party images before they enter an internal registrynot Clerk
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Clerk
- Pricing scales with monthly retained users, which can grow expensive quickly for consumer apps with large user bases.
- Enterprise SSO connections beyond the first are billed as add-ons, adding cost for larger organizations.
- The Business tier's extra dashboard seats cost $20/month each, which adds up for larger teams.
- Enterprise-tier features like the 99.99% uptime SLA require annual contracts rather than flexible monthly billing.
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
Clerk
Free- HobbyFree
- 50,000 MRU limit per app
- Up to 3 dashboard seats
- Unlimited applications
- Pro$25/month
- 50,000 MRUs included, $0.02/MRU overage
- Up to 3 dashboard seats
- 1 Enterprise Connection included
- Business$300/month
- 50,000 MRUs included with volume pricing
- 10 dashboard seats included
- SOC2 report and priority support
- Enterprise$undefined/month
- Custom pricing, annual billing
- 99.99% uptime SLA
- HIPAA available, dedicated Slack channel
Cosign
Free- CosignFree
- Apache-2.0
- Public Sigstore infrastructure free to use
- No usage limits published
Which should you pick?
Choose Clerk if
- You need prebuilt ui components.
- You want to start without paying.
- You work on web, ios, android, api.
- You also want organization management.
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.
Questions people ask
- Is Clerk or Cosign better?
- Neither clearly leads. Clerk 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, Clerk or Cosign?
- Clerk starts at Free and Cosign at Free.
- Does Clerk or Cosign run on more platforms?
- Clerk runs on web, ios, android, api. Cosign runs on macOS, Linux, Windows, Docker.
- Can I use Clerk for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Clerk best used for?
- Clerk is most often used for adding sign-in and user profiles to a web or mobile app quickly, b2b saas apps needing organizations and role-based access, startups wanting prebuilt ui instead of building auth in-house, apps needing mfa and fraud detection out of the box. Of those, adding sign-in and user profiles to a web or mobile app quickly and b2b saas apps needing organizations and role-based access are not what Cosign is typically brought in for.
- What can Clerk do that Cosign cannot?
- Clerk covers Prebuilt UI components, Organization management, Multi-factor authentication, Social sign-on. Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations.
Answered from the vendors’ own pages
Clerk: What does Clerk cost?
Clerk's Hobby plan is free with a 50,000 MRU limit; Pro is $25/month ($20/month billed annually), Business is $300/month ($250 annually), and Enterprise uses custom annual pricing.
SourceCosign: 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.
Clerk: Is there a free plan and what are its limits?
Yes, the Hobby plan is free with a 50,000 monthly retained user (MRU) limit per app, up to 3 dashboard seats, and unlimited applications, with no credit card required.
SourceCosign: Is signing alone enough?
No. Verification is a command somebody runs. Without an admission controller enforcing it, an unsigned image still runs.
Clerk: How is usage metered?
Clerk meters by monthly retained users (MRUs) — users who return to the app at least a day after signing up — with overage billed at $0.02 per MRU beyond the included 50,000 on paid plans.
SourceCosign: 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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