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Developer Tools · head to head

Backstage vs Cosign

Backstage logo

Backstage

Developer Tools

Open source internal developer portal framework created and open sourced by Spotify

From
Free
Rated
-
Full reviewWebsite
Cosign logo

Cosign

Cybersecurity

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

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Backstage backstage is a framework rather than a product: there is no supported turnkey install, so getting to a usable portal means a TypeScript and React project your team owns, hosts and upgrades forever.; 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.
  • They diverge on capability: Backstage covers Software catalogue, Cosign covers Keyless signing.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Backstage and Cosign actually diverge.

Attributes where Backstage and Cosign differ
AttributeBackstageCosign
PlatformsWeb, Self-hosted, Linux, Docker, KubernetesmacOS, Linux, Windows, Docker
CategoryDeveloper ToolsCybersecurity

Identical on both: starting price (Free), pricing model (Open source, no licence fee), 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 Backstage

  • Software catalogue
  • Software templates
  • TechDocs
  • Plugin architecture
  • Kubernetes plugin
  • Search
  • Entity ownership model
  • Auth provider integrations

Only in Cosign

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

What people use each for

The jobs each tool is most often brought in to do.

Backstage

  • An engineering organisation past roughly a hundred services where nobody can reliably answer who owns a given service at two in the morningnot Cosign
  • A platform team enforcing golden paths, so a new service is scaffolded with logging, CI and security defaults already wired innot Cosign
  • A company consolidating scattered READMEs and Confluence pages into docs that live beside the code and cannot silently rot unnoticednot Cosign
  • A regulated business that needs an auditable register of every running service, its owner and its data classificationnot Cosign

Cosign

  • Signing container images in a build pipeline without managing long-lived private keysnot Backstage
  • Attaching a signed bill of materials to a release so consumers can verify its provenancenot Backstage
  • Meeting a customer or regulatory requirement for signed artifactsnot Backstage
  • Verifying third-party images before they enter an internal registrynot Backstage

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Backstage

  • Backstage is a framework rather than a product: there is no supported turnkey install, so getting to a usable portal means a TypeScript and React project your team owns, hosts and upgrades forever.
  • Upstream releases move quickly and plugin APIs have broken across major versions, so a customised deployment accumulates upgrade debt and teams routinely fall months behind on versions they cannot cheaply catch up on.
  • The catalogue is only as good as the YAML descriptors engineers remember to write; without enforcement the register drifts out of date, and a developer portal nobody trusts is abandoned faster than one that never existed.
  • Community plugin quality varies sharply, with many unmaintained or pinned to old core versions, so the plugin that made the business case may be the one blocking your next upgrade.
  • Spotify Portal, the packaged commercial route, publishes no price at all and is quoted as a custom annual subscription, so the only cost you can actually forecast up front is the self-hosted one, which is the option with the largest hidden staffing bill.

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.

Pricing, plan by plan

Backstage

Free
  • Backstage (open source)Free
    • Apache 2.0 licence
    • Software catalogue, templates, TechDocs and search
    • Full plugin ecosystem
  • Spotify Portal for Backstage$undefined/year
    • Packaged commercial distribution from Spotify
    • Spotify premium plugins including Soundcheck and Insights
    • Simplified setup and managed upgrade path

Cosign

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

Which should you pick?

Choose Backstage if

  • You need software catalogue.
  • You want to start without paying.
  • You work on Web, Self-hosted, Linux, Docker, Kubernetes.
  • You also want software templates.
Backstage review

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

Questions people ask

Is Backstage or Cosign better?
Neither clearly leads. Backstage starts at Free and Cosign at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Backstage or Cosign?
Backstage starts at Free and Cosign at Free.
Does Backstage or Cosign run on more platforms?
Backstage runs on Web, Self-hosted, Linux, Docker, Kubernetes. Cosign runs on macOS, Linux, Windows, Docker.
Can I use Backstage for free?
Both have a free tier, so you can try either at no cost before committing.
What is Backstage best used for?
Backstage is most often used for an engineering organisation past roughly a hundred services where nobody can reliably answer who owns a given service at two in the morning, a platform team enforcing golden paths, so a new service is scaffolded with logging, ci and security defaults already wired in, a company consolidating scattered readmes and confluence pages into docs that live beside the code and cannot silently rot unnoticed, a regulated business that needs an auditable register of every running service, its owner and its data classification. Of those, an engineering organisation past roughly a hundred services where nobody can reliably answer who owns a given service at two in the morning and a platform team enforcing golden paths, so a new service is scaffolded with logging, ci and security defaults already wired in are not what Cosign is typically brought in for.
What can Backstage do that Cosign cannot?
Backstage covers Software catalogue, Software templates, TechDocs, Plugin architecture. Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations.

Answered from the vendors’ own pages

Backstage: Is Backstage free?

The project is Apache 2.0 with no licence fee. The real cost is engineering time; teams commonly dedicate one to two engineers permanently to running it.

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.

Backstage: Do I need to write code to use it?

Yes. Configuring and extending a Backstage application is a TypeScript and React project. This is the single most common misjudgement buyers make.

Cosign: Is signing alone enough?

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

Backstage: What is Spotify Portal for Backstage?

A commercial distribution from Spotify with premium plugins and support, generally available since October 2025 and sold as a quoted annual subscription with no published price.

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.

Backstage: Who owns the project?

Spotify created and open sourced it; it is now a CNCF project, so the upstream roadmap is not solely Spotify controlled.

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.

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