Cybersecurity · head to head
Cosign vs Flagsmith
Cosign
Cybersecurity
Signs and verifies container images and artifacts, with or without managing keys
- From
- Free
- Rated
- -
Flagsmith
Software Development
Open-source feature flag and remote config platform
- From
- Free
- Rated
- -
The short version
- Each has a real cost: 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.; Flagsmith the Free plan supports only a single team member, limiting collaboration for small teams.
- They diverge on capability: Cosign covers Keyless signing, Flagsmith covers Feature flags.
- Prices and features above were last checked on 31 August 2026.
Where they differ
Only the attributes on which Cosign and Flagsmith actually diverge.
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).
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 Cosign
- Keyless signing
- Key and KMS signing
- Registry-native storage
- In-toto attestations
- Offline verification
- Trusted root and signing config
Only in Flagsmith
- Feature flags
- Segments
- A/B testing
- Scheduled flags
- SDKs
- SAML/SSO
What people use each for
The jobs each tool is most often brought in to do.
Cosign
- Signing container images in a build pipeline without managing long-lived private keysnot Flagsmith
- Attaching a signed bill of materials to a release so consumers can verify its provenancenot Flagsmith
- Meeting a customer or regulatory requirement for signed artifactsnot Flagsmith
- Verifying third-party images before they enter an internal registrynot Flagsmith
Flagsmith
- Gradual feature rollouts across environmentsnot Cosign
- Remote configuration without redeploying codenot Cosign
- Running A/B tests tied to feature flagsnot Cosign
- Self-hosting feature flags for data residency requirementsnot Cosign
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
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.
Flagsmith
- The Free plan supports only a single team member, limiting collaboration for small teams.
- Exceeding request limits triggers overage charges after a one-time 30-day grace period.
- Enterprise-grade SSO and governance are locked behind the Scale-Up and Enterprise tiers.
- Self-hosting requires operating and updating the platform yourself, unlike a fully managed SaaS competitor.
Pricing, plan by plan
Cosign
Free- CosignFree
- Apache-2.0
- Public Sigstore infrastructure free to use
- No usage limits published
Flagsmith
Free- FreeFree
- Up to 50,000 requests/month
- 1 team member
- Unlimited feature flags, environments, identities and segments
- Start-Up$45/month
- Up to 1,000,000 requests/month
- 3 team members
- Scheduled flags, 2FA, A/B testing, integrations, email support
- Scale-Up$300/month
- 5,000,000+ requests/month
- 5-20 team members
- SAML/SSO, governance features, priority support
Which should you pick?
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.
Choose Flagsmith if
- You need feature flags.
- You want to start without paying.
- You work on web, api.
- You also want segments.
Questions people ask
- Is Cosign or Flagsmith better?
- Neither clearly leads. Cosign starts at Free and Flagsmith at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Cosign or Flagsmith?
- Cosign starts at Free and Flagsmith at Free.
- Does Cosign or Flagsmith run on more platforms?
- Cosign runs on macOS, Linux, Windows, Docker. Flagsmith runs on web, api.
- Can I use Cosign for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Cosign best used for?
- Cosign is most often used for signing container images in a build pipeline without managing long-lived private keys, attaching a signed bill of materials to a release so consumers can verify its provenance, meeting a customer or regulatory requirement for signed artifacts, verifying third-party images before they enter an internal registry. Of those, signing container images in a build pipeline without managing long-lived private keys and attaching a signed bill of materials to a release so consumers can verify its provenance are not what Flagsmith is typically brought in for.
- What can Cosign do that Flagsmith cannot?
- Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations. Flagsmith covers Feature flags, Segments, A/B testing, Scheduled flags.
Answered from the vendors’ own pages
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.
Flagsmith: What does Flagsmith cost?
Flagsmith has a Free plan, a Start-Up plan from $40-45/month, a Scale-Up plan from $250-300/month, and custom Enterprise pricing.
SourceCosign: Is signing alone enough?
No. Verification is a command somebody runs. Without an admission controller enforcing it, an unsigned image still runs.
Flagsmith: Is there a free plan, and what are its limits?
The Free plan supports up to 50,000 requests per month and 1 team member, with unlimited feature flags, environments, identities and segments.
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.
Flagsmith: How is usage metered?
Usage is metered by monthly API requests; exceeding a plan's limit triggers overage charges starting around $50 per million requests, with a 30-day grace period the first time a paid plan exceeds its limit.
SourceCosign: 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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