Softwr

Cybersecurity · head to head

Cosign vs OpenCities

Cosign logo

Cosign

Cybersecurity

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

From
Free
Free plan
Yes
Full reviewWebsite
OpenCities logo

OpenCities

Government

Digital Government Experience Platform

From
$500/month
Free plan
No
Full reviewWebsite

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.; OpenCities population-based pricing model limits scalability for growing municipalities
  • They diverge on capability: Cosign covers Keyless signing, OpenCities covers Website Management.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Cosign and OpenCities actually diverge.

Attributes where Cosign and OpenCities differ
AttributeCosignOpenCities
Starting priceFree$500/month
Pricing modelOpen source, no licence feesubscription
Free tierYesNo
PlatformsmacOS, Linux, Windows, DockerWeb, Mobile
CategoryCybersecurityGovernment
FoundedUnknown2008

Identical on both: 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 OpenCities

  • Website Management
  • Digital Forms
  • Search Optimization
  • Accessibility Compliance
  • Analytics
  • Salesforce
  • Microsoft 365
  • Google Analytics

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

OpenCities

  • Citizen Servicesnot Cosign
  • Records Managementnot Cosign
  • Public Safetynot Cosign
  • Civic Engagementnot 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.

OpenCities

  • Population-based pricing model limits scalability for growing municipalities
  • No self-hosted or on-premises deployment option
  • Limited code customization without vendor support

Pricing, plan by plan

Cosign

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

OpenCities

$500/month
  • Government Platform$500/month
    • Website CMS
    • Digital Forms
    • Accessibility

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 OpenCities if

  • You need website management.
  • You work on Web, Mobile.
  • You also want digital forms.
OpenCities review

Questions people ask

Is Cosign or OpenCities better?
Neither clearly leads. Cosign starts at Free and OpenCities at $500/month, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Cosign or OpenCities?
Cosign has a free tier; the other does not. Paid plans start at Free for Cosign and $500/month for OpenCities.
Does Cosign or OpenCities run on more platforms?
Cosign runs on macOS, Linux, Windows, Docker. OpenCities runs on Web, Mobile.
Can I use Cosign for free?
Yes. Cosign has a free tier, so you can try it without paying. OpenCities starts at $500/month.
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 OpenCities is typically brought in for.
What can Cosign do that OpenCities cannot?
Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations. OpenCities covers Website Management, Digital Forms, Search Optimization, Accessibility Compliance.

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.

OpenCities: Does OpenCities work offline?

No, OpenCities is a cloud-based SaaS platform that requires an internet connection. All editing and management is done through web browsers.

Source
Cosign: Is signing alone enough?

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

OpenCities: What accessibility standards does OpenCities meet?

OpenCities is maintained to comply with WCAG AA requirements, ensuring equitable access to government services and information for all residents.

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.

OpenCities: Can I integrate OpenCities with other government systems?

Yes. OpenCities integrates with Google Analytics, govDelivery for notifications, EngagementHQ for feedback collection, Legistar for meeting management, and Active Directory for intranet workflows.

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.

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.

Share

Related pages

More on Cosign

More on OpenCities

Keep looking

Other head to heads