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Cybersecurity · head to head

Cosign vs Infracost

Cosign logo

Cosign

Cybersecurity

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

From
Free
Rated
-
Full reviewWebsite
Infracost logo

Infracost

Cloud

Cloud cost estimates in pull requests, with governance in the paid tier

From
Free
Rated
-
Full reviewWebsite

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.; Infracost usage-based resources such as object storage, serverless functions and data transfer have no cost without monthly usage figures supplied by hand, and the documentation warns plainly that engineers otherwise read them as free.
  • They diverge on capability: Cosign covers Keyless signing, Infracost covers Pull request cost diffs.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Cosign and Infracost actually diverge.

Attributes where Cosign and Infracost differ
AttributeCosignInfracost
Pricing modelOpen source, no licence feeFree open source tool, then per month by run volume
PlatformsmacOS, Linux, Windows, DockerWeb, macOS, Linux, Windows, Docker
CategoryCybersecurityCloud

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 Infracost

  • Pull request cost diffs
  • Multi-format parsing
  • Apache-2.0 CLI
  • FinOps policies
  • Automated remediation
  • IDE integration

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 Infracost
  • Attaching a signed bill of materials to a release so consumers can verify its provenancenot Infracost
  • Meeting a customer or regulatory requirement for signed artifactsnot Infracost
  • Verifying third-party images before they enter an internal registrynot Infracost

Infracost

  • Teams that want an expensive infrastructure change questioned at review rather than discovered on an invoicenot Cosign
  • Platform groups enforcing tagging so cloud spend can be attributed to a team at allnot Cosign
  • Organisations adopting FinOps practice without buying a full cloud management platformnot Cosign
  • Engineers who want a cost figure in the editor while writing the Terraformnot 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.

Infracost

  • Usage-based resources such as object storage, serverless functions and data transfer have no cost without monthly usage figures supplied by hand, and the documentation warns plainly that engineers otherwise read them as free.
  • Splitting production from non-production usage assumptions is not supported in the free usage file, which the docs attribute to a missing project filter, so that separation requires the paid product.
  • The step from 250 to 1,000 dollars a month is large and the Cloud tier includes only ten admin seats, with developer seats charged at a figure that is not published, so the cost for a large organisation cannot be computed from the pricing page.
  • Estimates are list price. Negotiated agreements, committed use discounts and reserved instance economics require SKU-level overrides available only on Enterprise, so the number in the pull request is not the number on the bill.
  • The share of the product covered by the Apache-2.0 licence is shrinking. Checks, automated fixes, policies and agent integrations are all hosted-only, so the permissive licence increasingly protects the estimation engine rather than the product.

Pricing, plan by plan

Cosign

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

Infracost

Free
  • FreeFree
    • 1,000 runs a month
    • Terraform, CloudFormation and CDK estimates
    • Community support
  • Starter$250/month
    • 10,000 runs a month
    • Email support
  • Cloud$1000/month
    • Ten admin seats, developer seats charged separately
    • FinOps policies and cost guardrails
    • Dashboards and audit trails
  • Enterprise$undefined/year
    • SKU-level price overrides for negotiated rates
    • Business unit reporting
    • SSO with SAML group mapping

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.
Cosign review

Choose Infracost if

  • You need pull request cost diffs.
  • You want to start without paying.
  • You work on Web, macOS, Linux, Windows, Docker.
  • You also want multi-format parsing.
Infracost review

Questions people ask

Is Cosign or Infracost better?
Neither clearly leads. Cosign starts at Free and Infracost at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Cosign or Infracost?
Cosign starts at Free and Infracost at Free.
Does Cosign or Infracost run on more platforms?
Cosign runs on macOS, Linux, Windows, Docker. Infracost runs on Web, macOS, Linux, Windows, Docker.
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 Infracost is typically brought in for.
What can Cosign do that Infracost cannot?
Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations. Infracost covers Pull request cost diffs, Multi-format parsing, Apache-2.0 CLI, FinOps policies.

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.

Infracost: Is the open source version genuinely useful on its own?

Yes, for estimation. It parses your definitions and produces breakdowns and diffs locally. What it does not do is comment on pull requests, enforce policy or report across an organisation, all of which are hosted-only.

Cosign: Is signing alone enough?

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

Infracost: Will the estimate match my cloud bill?

No. It is list price. Committed use discounts, enterprise agreements and reserved instances need SKU-level overrides that sit in the Enterprise tier.

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.

Infracost: Why do my S3 and Lambda resources show no cost?

Usage-based resources need monthly usage values supplied in a usage file or defined centrally. Without them they estimate at zero, which is the documented behaviour and the most common way the tool misleads.

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.

Infracost: Has the licence ever changed?

No. The command line tool has been Apache 2.0 throughout, with no Business Source or AGPL episode, which is unusual in this category.

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.

Infracost: What is a run?

Not defined on the public pricing page, and the run allowance is what separates the free and Starter tiers, so establish the definition before choosing between them.

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