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Cybersecurity · head to head

Cosign vs Semgrep

Cosign logo

Cosign

Cybersecurity

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

From
Free
Rated
-
Full reviewWebsite
Semgrep logo

Semgrep

Cybersecurity

Open-source static analysis tool for finding security bugs and enforcing code standards.

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.; Semgrep free tier caps out at 10 contributors and 10 repositories.
  • They diverge on capability: Cosign covers Keyless signing, Semgrep covers Static code scanning.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Cosign and Semgrep actually diverge.

Attributes where Cosign and Semgrep differ
AttributeCosignSemgrep
Pricing modelOpen source, no licence feefreemium
PlatformsmacOS, Linux, Windows, Dockerweb, api, linux, mac, windows

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 Cosign

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

Only in Semgrep

  • Static code scanning
  • Supply chain scanning
  • Secrets detection
  • Cross-file analysis
  • AI-powered triage and remediation
  • CI/CD 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 Semgrep
  • Attaching a signed bill of materials to a release so consumers can verify its provenancenot Semgrep
  • Meeting a customer or regulatory requirement for signed artifactsnot Semgrep
  • Verifying third-party images before they enter an internal registrynot Semgrep

Semgrep

  • Scanning code for security vulnerabilities in CI/CDnot Cosign
  • Detecting vulnerable open-source dependenciesnot Cosign
  • Finding hardcoded secrets before code shipsnot Cosign
  • Enforcing custom code standards with rule setsnot Cosign
  • Prioritizing findings with AI-assisted triagenot 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.

Semgrep

  • Free tier caps out at 10 contributors and 10 repositories.
  • Secrets scanning is priced as a separate module ($15/contributor) from Code and Supply Chain.
  • Self-managed repositories and custom CI/CD require the Enterprise tier.
  • AI credits are limited per tier and additional usage requires upgrading.

Pricing, plan by plan

Cosign

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

Semgrep

Free
  • FreeFree
    • Up to 10 contributors
    • Code and Supply Chain scanning
    • 60 AI credits total
  • Teams$30/month
    • Code, Supply Chain, or Secrets scanning per contributor
    • Pro rules
    • AI-powered triage and remediation
  • Enterprise$undefined/month
    • On-prem support
    • Custom CI/CD
    • 50 AI credits per developer/month

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 Semgrep if

  • You need static code scanning.
  • You want to start without paying.
  • You work on web, api, linux, mac, windows.
  • You also want supply chain scanning.
Semgrep review

Questions people ask

Is Cosign or Semgrep better?
Neither clearly leads. Cosign starts at Free and Semgrep at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Cosign or Semgrep?
Cosign starts at Free and Semgrep at Free.
Does Cosign or Semgrep run on more platforms?
Cosign runs on macOS, Linux, Windows, Docker. Semgrep runs on web, api, linux, mac, windows.
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 Semgrep is typically brought in for.
What can Cosign do that Semgrep cannot?
Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations. Semgrep covers Static code scanning, Supply chain scanning, Secrets detection, Cross-file analysis.

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.

Semgrep: What does Semgrep cost?

The Free edition covers up to 10 contributors; Teams starts at $30/contributor/month for Code scanning (Supply Chain also $30, Secrets $15); Enterprise is custom-priced.

Source
Cosign: Is signing alone enough?

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

Semgrep: Is there a free plan, and what are its limits?

Yes, the Free edition supports up to 10 contributors and 10 repositories with Code and Supply Chain scanning plus 60 AI credits total.

Source
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.

Semgrep: How is usage metered?

Pricing is per contributor, defined as someone who made at least one commit to a scanned private repository in the past 90 days.

Source
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.

Semgrep: Is there special pricing for startups?

Yes, Semgrep offers special startup pricing upon request for early-stage companies.

Source
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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