Cybersecurity · head to head
Cosign vs Microsoft Defender for Endpoint
Cosign
Cybersecurity
Signs and verifies container images and artifacts, with or without managing keys
- From
- Free
- Rated
- -
Microsoft Defender for Endpoint
Cybersecurity
Enterprise endpoint security built into Microsoft 365
- From
- On request
- Rated
- -
The short version
- Only Cosign has a free tier, so it costs nothing to try first.
- 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.; Microsoft Defender for Endpoint pricing not published on public websites; quote required from Microsoft sales
- They diverge on capability: Cosign covers Keyless signing, Microsoft Defender for Endpoint covers Threat & vulnerability management.
- Prices and features above were last checked on 31 August 2026.
Where they differ
Only the attributes on which Cosign and Microsoft Defender for Endpoint actually diverge.
| Attribute | Cosign | Microsoft Defender for Endpoint |
|---|---|---|
| Starting price | Free | On request |
| Pricing model | Open source, no licence fee | quote |
| Free tier | Yes | No |
| Platforms | macOS, Linux, Windows, Docker | Windows, macOS, Linux, iOS, Android |
| Founded | Unknown | 1975 |
Identical on both: 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 Microsoft Defender for Endpoint
- Threat & vulnerability management
- Attack surface reduction
- Next-gen protection
- EDR
- Auto investigation
- Microsoft Threat Experts
- Threat analytics
- Secure score
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 Microsoft Defender for Endpoint
- Attaching a signed bill of materials to a release so consumers can verify its provenancenot Microsoft Defender for Endpoint
- Meeting a customer or regulatory requirement for signed artifactsnot Microsoft Defender for Endpoint
- Verifying third-party images before they enter an internal registrynot Microsoft Defender for Endpoint
Microsoft Defender for Endpoint
- Enterprise endpoint security across Windows, macOS, Linux, Android, and iOS via Plans 1 or 2not Cosign
- Small and medium-sized businesses using Microsoft Defender for Business as alternativenot Cosign
- Organisations using Microsoft 365 E5 which includes Defender for Endpoint Plan 2not 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.
Microsoft Defender for Endpoint
- Pricing not published on public websites; quote required from Microsoft sales
- Defender for Endpoint Plan 1 and Plan 2 do not include server licenses; additional licensing required for server protection
- Specific feature differences between Plan 1 and Plan 2 require consulting Microsoft documentation
Pricing, plan by plan
Cosign
Free- CosignFree
- Apache-2.0
- Public Sigstore infrastructure free to use
- No usage limits published
Microsoft Defender for Endpoint
On requestNo published plan breakdown. See the Microsoft Defender for Endpoint review.
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 Microsoft Defender for Endpoint if
- You need threat & vulnerability management.
- You work on Windows, macOS, Linux, iOS, Android.
- You also want attack surface reduction.
Questions people ask
- Is Cosign or Microsoft Defender for Endpoint better?
- Neither clearly leads. Cosign starts at Free and Microsoft Defender for Endpoint at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Cosign or Microsoft Defender for Endpoint?
- Cosign has a free tier; the other does not. Paid plans start at Free for Cosign and On request for Microsoft Defender for Endpoint.
- Does Cosign or Microsoft Defender for Endpoint run on more platforms?
- Cosign runs on macOS, Linux, Windows, Docker. Microsoft Defender for Endpoint runs on Windows, macOS, Linux, iOS, Android.
- Can I use Cosign for free?
- Yes. Cosign has a free tier, so you can try it without paying. Microsoft Defender for Endpoint starts at On request.
- 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 Microsoft Defender for Endpoint is typically brought in for.
- What can Cosign do that Microsoft Defender for Endpoint cannot?
- Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations. Microsoft Defender for Endpoint covers Threat & vulnerability management, Attack surface reduction, Next-gen protection, EDR.
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.
Microsoft Defender for Endpoint: How is Microsoft Defender for Endpoint priced?
Defender for Endpoint is bundled into Microsoft 365 enterprise subscriptions. Plan 1 is included in Microsoft 365 E3, and Plan 2 is included in Microsoft 365 E5. Individual pricing is not published separately.
SourceCosign: Is signing alone enough?
No. Verification is a command somebody runs. Without an admission controller enforcing it, an unsigned image still runs.
Microsoft Defender for Endpoint: Does Microsoft Defender for Endpoint offer a trial?
Yes. A free trial is available for prospective customers to test the product before committing to a subscription.
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.
Microsoft Defender for Endpoint: What is the difference between Plan 1 and Plan 2?
Plan 1 (in E3) includes unified security tools, device controls, network protection, firewall, web/URL controls, APIs, SIEM connectors, and app controls. Plan 2 (in E5) adds endpoint detection and response, deception techniques, automatic attack disruption, exposure management, and threat intelligence.
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.
Related pages
More on Microsoft Defender for Endpoint
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