Cosign

Cosign is the command-line client of the Sigstore project for signing, verifying, and storing container images, OCI artifacts, blobs, and in-toto attestations. Cosign supports keyless signing using OpenID Connect identity providers (Google, GitHub, Microsoft) by obtaining short-lived certificates from the Fulcio certificate authority and recording signing events in the Rekor transparency log. Signatures and attestations are stored alongside the signed artifact in any OCI-compliant registry, and cosign integrates with policy controllers, KMS providers, hardware tokens, and SBOM workflows for software supply chain security.

Cosign publishes 2 APIs on the APIs.io network: Sigstore Rekor API (consumed) and Sigstore Fulcio API (consumed). Tagged areas include Apache 2.0, Attestations, CLI, Code Signing, and Containers.

Cosign’s developer surface includes documentation, getting-started guide, release notes, engineering blog, CLI, changelog, sandbox, and 31 more developer resources.

🌐 Visit website 📡 Source on GitHub

39.8/100 developing ▬ flat Agent 22/100 agent aware Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

AccessFreemium

3 APIs

Apache 2.0 Attestations CLI Code Signing ContainersFulcioGo Keyless OCI OIDC Open-SourceRekorSigstore Supply Chain Transparency Log Verification

Kin Score

Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0

Composite quality — 39.8/100 · developing

Contract Quality 6.7 / 25

Developer Ergonomics 15.6 / 20

Access Clarity 1.6 / 20

Operational Transparency 6.5 / 13

Contract Governance 2.2 / 12

Discoverability 7.2 / 10

Agent readiness — 22/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/cosign: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 3

Individual APIs this provider publishes, each with its own machine-readable definition.

Cosign CLI

Cosign is a command-line tool for signing, verifying, and storing container images and OCI artifacts. It supports keyless signing, hardware-backed keys, KMS providers, in-toto a...

Sigstore Rekor API (consumed)

Rekor is the Sigstore transparency log that cosign writes to and reads from when recording and verifying signing events. The public Rekor service exposes a REST API at rekor.sig...

Sigstore Fulcio API (consumed)

Fulcio is the Sigstore certificate authority that issues short-lived X.509 code-signing certificates bound to OIDC identities. Cosign calls the Fulcio public CA at fulcio.sigsto...

Pricing Plans 1

Published pricing tiers and plan structures.

Cosign Plans Pricing

0 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Cosign Rate Limits

0 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Cosign Finops

FINOPS

Security Posture 3

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Cosign Authentication

6 schemes

SECURITY

Cosign Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Cosign Vulnerability Disclosure

Hackerone

SECURITY

Resources

Get Started 3

Portal, sign-up, and the first successful call

GettingStarted

GettingStarted

DeveloperPortal

DeveloperPortal

Sandbox

Sandbox

Documentation 2

Reference material describing how the API behaves

ContributionGuide

ContributionGuide

Documentation

Documentation

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

AgentSkill

AgentSkill

X-MCPServerCandidate

X-MCPServerCandidate

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Lifecycle

Conformance

Conventions

ErrorCatalog

DataModel

Build 6

SDKs, sample code, and the tooling you integrate with

CodeOfConduct

CodeOfConduct

GitHubOrganization

GitHubRepository

Packages

SDKs

CLI

Access & Security 4

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Security

Security

VulnerabilityDisclosure

VulnerabilityDisclosure

Authentication

Authentication

Operate 9

Status, limits, changes, and where to get help

IssueTracker

ReleaseNotes

Community

Slack

RoadMap

ChangeLog

StatusPage

Deprecation

RateLimits

Scroll for all 9

Commercial 2

Pricing, plans, and the legal terms of use

License

License

Plans

Plans

Company 3

The organization behind the API

LinkedIn

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Installation

Installation

Source (apis.yml)

aid: cosign
name: Cosign
kind: opensource
description: Cosign is the command-line client of the Sigstore project for signing, verifying, and storing container images,
  OCI artifacts, blobs, and in-toto attestations. Cosign supports keyless signing using OpenID Connect identity providers
  (Google, GitHub, Microsoft) by obtaining short-lived certificates from the Fulcio certificate authority and recording signing
  events in the Rekor transparency log. Signatures and attestations are stored alongside the signed artifact in any OCI-compliant
  registry, and cosign integrates with policy controllers, KMS providers, hardware tokens, and SBOM workflows for software
  supply chain security.
url: https://raw.githubusercontent.com/api-evangelist/cosign/refs/heads/main/apis.yml
deliveryModel:
  model: unknown
  open_source: unknown
  commercial: false
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - repository-unlicensed
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/cosign.png
type: Index
access: Public
position: Producing
tags:
- Apache 2.0
- Attestations
- CLI
- Code Signing
- Containers
- Fulcio
- Go
- Keyless
- OCI
- OIDC
- Open-Source
- Rekor
- Sigstore
- Supply Chain
- Transparency Log
- Verification
tags_raw:
- Apache 2.0
- Attestations
- CLI
- Code Signing
- Containers
- Fulcio
- Go
- Keyless
- OCI
- OIDC
- Open Source
- Rekor
- Sigstore
- Supply Chain
- Transparency Log
- Verification
created: '2026-03-26'
modified: '2026-09-07'
specificationVersion: '0.23'
apis:
- aid: cosign:cosign-cli
  name: Cosign CLI
  description: Cosign is a command-line tool for signing, verifying, and storing container images and OCI artifacts. It supports
    keyless signing, hardware-backed keys, KMS providers, in-toto and SLSA attestations, and transparency log inclusion. The
    CLI is the primary user interface and does not expose its own HTTP API.
  humanURL: https://docs.sigstore.dev/cosign/
  properties:
  - type: Documentation
    url: https://docs.sigstore.dev/cosign/
  - type: GettingStarted
    url: https://docs.sigstore.dev/quickstart/quickstart-cosign/
  - type: Installation
    url: https://docs.sigstore.dev/cosign/system_config/installation/
  - type: GitHubRepository
    url: https://github.com/sigstore/cosign
  - type: Reference
    url: https://github.com/sigstore/cosign/tree/main/doc
  tags:
  - CLI
  - Containers
  - Keyless
  - OCI
  - Signing
- aid: cosign:rekor-api
  name: Sigstore Rekor API (consumed)
  description: 'Rekor is the Sigstore transparency log that cosign writes to and reads from when recording and verifying signing
    events. The public Rekor service exposes a REST API at rekor.sigstore.dev with operations for creating log entries, retrieving
    entries by index or UUID, fetching log info and proofs, and searching the index. Ownership: Rekor is a sibling project
    of Cosign inside the same GitHub organization (github.com/sigstore) and the same OpenSSF Sigstore project. It is recorded
    here as a CONSUMED dependency of the Cosign CLI, not as an API Cosign produces; the Rekor contract is profiled in its
    own right under all/sigstore.'
  humanURL: https://docs.sigstore.dev/logging/overview/
  baseURL: https://rekor.sigstore.dev
  properties:
  - type: Documentation
    url: https://docs.sigstore.dev/logging/overview/
  - type: OpenAPI
    url: https://raw.githubusercontent.com/sigstore/rekor/main/openapi.yaml
  - type: GitHubRepository
    url: https://github.com/sigstore/rekor
  tags:
  - Rekor
  - REST
  - Sigstore
  - Transparency Log
- aid: cosign:fulcio-api
  name: Sigstore Fulcio API (consumed)
  description: 'Fulcio is the Sigstore certificate authority that issues short-lived X.509 code-signing certificates bound
    to OIDC identities. Cosign calls the Fulcio public CA at fulcio.sigstore.dev during keyless signing to obtain a certificate
    for a verified identity. Ownership: Fulcio is a sibling project of Cosign inside the same GitHub organization (github.com/sigstore)
    and the same OpenSSF Sigstore project; its published contract at fulcio.swagger.json declares host fulcio.sigstore.dev,
    matching the baseURL below. It is recorded here as a CONSUMED dependency of the Cosign CLI, not as an API Cosign produces.'
  humanURL: https://docs.sigstore.dev/certificate_authority/overview/
  baseURL: https://fulcio.sigstore.dev
  properties:
  - type: Documentation
    url: https://docs.sigstore.dev/certificate_authority/overview/
  - type: OpenAPI
    url: https://raw.githubusercontent.com/sigstore/fulcio/main/fulcio.swagger.json
  - type: GitHubRepository
    url: https://github.com/sigstore/fulcio
  tags:
  - CA
  - Certificates
  - Fulcio
  - OIDC
  - Sigstore
common:
- type: IssueTracker
  url: https://github.com/sigstore/cosign/issues
- type: CodeOfConduct
  url: https://github.com/sigstore/cosign/blob/main/CODE_OF_CONDUCT.md
- type: ContributionGuide
  url: https://github.com/sigstore/cosign/blob/main/CONTRIBUTING.md
- type: DomainSecurity
  url: security/cosign-domain-security.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/sigstore
- type: Website
  url: https://www.sigstore.dev/
- type: Documentation
  url: https://docs.sigstore.dev/cosign/
- type: GettingStarted
  url: https://docs.sigstore.dev/quickstart/quickstart-cosign/
- type: Installation
  url: https://docs.sigstore.dev/cosign/system_config/installation/
- type: GitHubOrganization
  url: https://github.com/sigstore
- type: GitHubRepository
  url: https://github.com/sigstore/cosign
- type: ReleaseNotes
  url: https://github.com/sigstore/cosign/releases
- type: Blog
  url: https://blog.sigstore.dev/
- type: Community
  url: https://www.sigstore.dev/community
- type: Slack
  url: https://sigstore.slack.com/
- type: License
  url: https://github.com/sigstore/cosign/blob/main/LICENSE
- type: Security
  url: https://github.com/sigstore/cosign/security
- type: RoadMap
  url: https://github.com/sigstore/community/blob/main/ROADMAP.md
- type: DeveloperPortal
  url: https://docs.sigstore.dev/
- type: Packages
  url: packages/cosign-packages.yml
- type: SDKs
  url: packages/cosign-packages.yml
- type: CLI
  url: cli/cosign-cli.yml
- type: ChangeLog
  url: changelog/cosign-changelog.yml
- type: Lifecycle
  url: lifecycle/cosign-lifecycle.yml
- type: StatusPage
  url: https://status.sigstore.dev/
- type: Deprecation
  url: https://github.com/sigstore/cosign/blob/main/VERSIONING.md
- type: VulnerabilityDisclosure
  url: security/cosign-vulnerability-disclosure.yml
- type: Conformance
  url: conformance/cosign-conformance.yml
- type: Sandbox
  url: sandbox/cosign-sandbox.yml
- type: Conventions
  url: conventions/cosign-conventions.yml
- type: ErrorCatalog
  url: errors/cosign-error-codes.yml
- type: Authentication
  url: authentication/cosign-authentication.yml
- type: DataModel
  url: data-model/cosign-data-model.yml
- type: LLMsTxt
  url: llms/cosign-llms.txt
- type: AgentSkill
  url: skills/_index.yml
- type: X-MCPServerCandidate
  url: mcp/cosign-mcp.yml
- type: Plans
  url: plans/cosign-plans-pricing.yml
- type: RateLimits
  url: rate-limits/cosign-rate-limits.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
x-enrichment:
  date: '2026-09-07'
  status: enriched
  artifacts_added: 18
  pass: local-v3
x-parent: sigstore
x-relationship: product

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