Sigstore

Sigstore is a set of free-to-use open source tools for signing, verifying, and protecting software supply chain artifacts. It provides a transparent and auditable signing infrastructure that eliminates the need for managing signing keys, making software supply chain security more accessible. The Sigstore ecosystem includes Cosign for artifact signing, Fulcio as the certificate authority, and Rekor as the cryptographically secure transparency log.

Sigstore publishes 6 API contracts indexed on the APIs.io network, including CA API, Entries API, Index API, and 3 more. Tagged areas include Certificate Authority, Code Signing, Containers, Cryptography, and Open Source.

The Sigstore catalog on APIs.io includes 1 JSON-LD context and 2 Spectral governance rulesets.

Sigstore’s developer surface includes documentation, getting-started guide, engineering blog, and 17 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

33.9/100 thin ▬ flat Agent 17/100 agent aware Heartbeat 100/100 alive self hosted · Apache-2.0 Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessFreemium

2 published contracts

Certificate Authority Code Signing Containers Cryptography Open Source PKI Security Software Supply Chain Transparency Log

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 33.9/100 · thin

Contract Quality 7.9 / 16

Developer Ergonomics 3.4 / 13

Access Clarity 0.7 / 13

Operational Transparency 2.9 / 8

Contract Governance 2.1 / 8

Discoverability 3.7 / 7

Regulatory Posture 1.6 / 15

Open Source Surface 6.5 / 10

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 17/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 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

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Open Source Surface applies to this provider. This product is open source and we read its repository directly, so Open Source Surface carries 10 points of the composite. It is scored from what the repository actually publishes — a security policy, a contribution guide, a release history, a code of conduct — read live from the provider rather than inferred from our own catalog pointers. This facet adds; nothing was taken away to make room for it. An open-source project is not excused from the commercial facets, because exemption would strip it of the points it does earn. If we have the wrong repository, or this product is not open source, say so on your provider repo and we will drop the facet rather than have you publish against it.

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 65 points between them, because both conditional facets apply and carry 35 points together. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 65% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link

10 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Access Clarity scores 5.3 — up to +18.9 composite points
Developer Ergonomics scores 26.2 — up to +14.8 composite points
Contract Quality scores 48.9 — up to +12.8 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

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 the provider profile at artifacts.apis.io/sigstore/apis.yml: open an issue on github.com/api-evangelist/sigstore to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
PKI and Encryption (certificate authorities, key management)	standard	55.6	-	-
Jenkins Plugins + CD Foundation Landscape	standard	55.6	-	-
OpenSSF Best Practices Badge Holders	standard	55.6	-	-
Artifact Hub Cloud-Native Packages	standard	55.6	-	-

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

OpenAPI

measured — observed by APIs.io (published)

APIs 6

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

Cosign

Cosign is the Sigstore tool for signing and verifying container images and other OCI artifacts. It enables keyless signing using OIDC identity, hardware token signing, and polic...

Sigstore CA API

The CA API from Sigstore — 3 operation(s) for ca.

Sigstore Entries API

The entries API from Sigstore — 3 operation(s) for entries.

Sigstore Index API

The index API from Sigstore — 1 operation(s) for index.

Sigstore Pubkey API

The pubkey API from Sigstore — 1 operation(s) for pubkey.

Sigstore Tlog API

The tlog API from Sigstore — 2 operation(s) for tlog.

Open Collections 6

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

Fulcio

OPEN COLLECTION

Fulcio CA API

OPEN COLLECTION

Fulcio CA entries API

OPEN COLLECTION

Fulcio CA index API

OPEN COLLECTION

Fulcio CA pubkey API

OPEN COLLECTION

Fulcio CA tlog API

OPEN COLLECTION

Sigstore API pricing

Not yet checked against Sigstore's own pricing page. Compiled by API Evangelist on 2026-05-05 from docs.sigstore.dev/; confirm before you rely on a figure. A free plan or tier is listed.

Plan	Price
Public-Good Service freemium	—

Plan details, limits and sources →

Rate limits

Public-good fair use: not publicly documented varies

Compiled by API Evangelist, not yet checked against Sigstore's documentation. Rate-limit details →

Pricing Plans 1

Published pricing tiers and plan structures.

Sigstore Plans Pricing

1 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Sigstore Rate Limits

1 limits

RATE LIMITS

Service Levels 1

Uptime the provider promises or reports, as SLA4OAI. Read from its own pages; APIs.io runs no monitors.

Sigstore

SLA

FinOps 1

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

Sigstore Finops

FINOPS

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Sigstore Context

30 classes · 2 properties

JSON-LD

Spectral Rules 2

Spectral governance rulesets for linting and validating these APIs.

Sigstore — jsonschema rules

5 rules · 3 warnings 2 info

SPECTRAL

Sigstore API Rules

6 rules · 1 errors 5 warnings

SPECTRAL

JSON Schema 2

Standalone JSON Schema definitions for this provider's data models.

Sigstore Fulcio Signing Certificate

2 properties

JSON SCHEMA

Sigstore Rekor Log Entry

6 properties

JSON SCHEMA

JSON Structure 1

JSON Structure definitions describing this provider's data shapes.

Sigstore Log Entry Structure

0 properties

JSON STRUCTURE

Examples 3

Example request and response payloads for these APIs.

Sigstore Create Log Entry Example

3 fields

EXAMPLE

Sigstore Get Signing Cert Example

3 fields

EXAMPLE

Sigstore Search Log Index Example

3 fields

EXAMPLE

Security Posture 1

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

Sigstore Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Sigstore Agentic Access

11 operations · 2 acting

AGENTIC

Resources

Get Started 1

Portal, sign-up, and the first successful call

GettingStarted

GettingStarted

Documentation 2

Reference material describing how the API behaves

ContributionGuide

ContributionGuide

Documentation

Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Design & Contract 1

Pagination, idempotency, versioning, errors, and events

Vocabulary

Vocabulary

Build 2

SDKs, sample code, and the tooling you integrate with

CodeOfConduct

CodeOfConduct

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Security

Security

Operate 4

Status, limits, changes, and where to get help

RateLimits

IssueTracker

Releases

Community

Commercial 3

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

License

License

Company 3

The organization behind the API

LinkedIn

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Policy Controller

Policy Controller

Source (apis.yml)

aid: sigstore
name: Sigstore
description: Sigstore is a set of free-to-use open source tools for signing, verifying, and protecting software supply chain
  artifacts. It provides a transparent and auditable signing infrastructure that eliminates the need for managing signing
  keys, making software supply chain security more accessible. The Sigstore ecosystem includes Cosign for artifact signing,
  Fulcio as the certificate authority, and Rekor as the cryptographically secure transparency log.
type: Index
deliveryModel:
  model: self-hosted
  license: Apache-2.0
  open_source: true
  commercial: false
  callable_host: true
  label: Self-hosted open source · you run it yourself
  confidence: high
  source:
  - license
  - openapi
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: low
  source:
  - plans
  - security
  generated: '2026-11-06'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/sigstore.png
tags:
- Certificate Authority
- Code Signing
- Containers
- Cryptography
- Open Source
- PKI
- Security
- Software Supply Chain
- Transparency Log
tags_raw:
- Certificate Authority
- Code Signing
- Containers
- Cryptography
- Open Source
- PKI
- Security
- Software Supply Chain
- Transparency Log
- Open-Source
url: https://raw.githubusercontent.com/api-evangelist/sigstore/refs/heads/main/apis.yml
created: '2026-03-26'
modified: '2026-05-19'
specificationVersion: '0.23'
apis:
- aid: sigstore:cosign
  name: Cosign
  description: Cosign is the Sigstore tool for signing and verifying container images and other OCI artifacts. It enables
    keyless signing using OIDC identity, hardware token signing, and policy enforcement for container supply chain security.
  humanURL: https://docs.sigstore.dev/cosign/signing/overview/
  tags:
  - Code Signing
  - Containers
  - OCI
  - Security
  - Software Supply Chain
  properties:
  - type: Documentation
    url: https://docs.sigstore.dev/cosign/signing/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/cosign
- aid: sigstore:sigstore-ca-api
  name: Sigstore CA API
  description: The CA API from Sigstore — 3 operation(s) for ca.
  humanURL: https://docs.sigstore.dev/logging/overview/
  baseURL: https://rekor.sigstore.dev
  tags:
  - CA
  properties:
  - type: OpenAPI
    url: openapi/sigstore-ca-api-openapi.yml
  - type: Documentation
    url: https://docs.sigstore.dev/logging/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/rekor
  - type: Rules
    url: https://raw.githubusercontent.com/api-evangelist/sigstore/refs/heads/main/rules/sigstore-rules.yml
  - type: Documentation
    url: https://docs.sigstore.dev/certificate_authority/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/fulcio
- aid: sigstore:sigstore-entries-api
  name: Sigstore Entries API
  description: The entries API from Sigstore — 3 operation(s) for entries.
  humanURL: https://docs.sigstore.dev/logging/overview/
  baseURL: https://rekor.sigstore.dev
  tags:
  - Entries
  tags_raw:
  - entries
  properties:
  - type: OpenAPI
    url: openapi/sigstore-entries-api-openapi.yml
  - type: Documentation
    url: https://docs.sigstore.dev/logging/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/rekor
  - type: Rules
    url: https://raw.githubusercontent.com/api-evangelist/sigstore/refs/heads/main/rules/sigstore-rules.yml
  - type: Documentation
    url: https://docs.sigstore.dev/certificate_authority/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/fulcio
- aid: sigstore:sigstore-index-api
  name: Sigstore Index API
  description: The index API from Sigstore — 1 operation(s) for index.
  humanURL: https://docs.sigstore.dev/logging/overview/
  baseURL: https://rekor.sigstore.dev
  tags:
  - Index
  tags_raw:
  - index
  properties:
  - type: OpenAPI
    url: openapi/sigstore-index-api-openapi.yml
  - type: Documentation
    url: https://docs.sigstore.dev/logging/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/rekor
  - type: Rules
    url: https://raw.githubusercontent.com/api-evangelist/sigstore/refs/heads/main/rules/sigstore-rules.yml
  - type: Documentation
    url: https://docs.sigstore.dev/certificate_authority/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/fulcio
- aid: sigstore:sigstore-pubkey-api
  name: Sigstore Pubkey API
  description: The pubkey API from Sigstore — 1 operation(s) for pubkey.
  humanURL: https://docs.sigstore.dev/logging/overview/
  baseURL: https://rekor.sigstore.dev
  tags:
  - Pubkey
  tags_raw:
  - pubkey
  properties:
  - type: OpenAPI
    url: openapi/sigstore-pubkey-api-openapi.yml
  - type: Documentation
    url: https://docs.sigstore.dev/logging/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/rekor
  - type: Rules
    url: https://raw.githubusercontent.com/api-evangelist/sigstore/refs/heads/main/rules/sigstore-rules.yml
  - type: Documentation
    url: https://docs.sigstore.dev/certificate_authority/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/fulcio
- aid: sigstore:sigstore-tlog-api
  name: Sigstore Tlog API
  description: The tlog API from Sigstore — 2 operation(s) for tlog.
  humanURL: https://docs.sigstore.dev/logging/overview/
  baseURL: https://rekor.sigstore.dev
  tags:
  - tlog
  properties:
  - type: OpenAPI
    url: openapi/sigstore-tlog-api-openapi.yml
  - type: Documentation
    url: https://docs.sigstore.dev/logging/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/rekor
  - type: Rules
    url: https://raw.githubusercontent.com/api-evangelist/sigstore/refs/heads/main/rules/sigstore-rules.yml
  - type: Documentation
    url: https://docs.sigstore.dev/certificate_authority/overview/
  - type: GitHubRepository
    url: https://github.com/sigstore/fulcio
common:
- type: Plans
  url: plans/sigstore-plans-pricing.yml
- type: RateLimits
  url: rate-limits/sigstore-rate-limits.yml
- type: FinOps
  url: finops/sigstore-finops.yml
- type: IssueTracker
  url: https://github.com/sigstore/cosign/issues
- type: Releases
  url: https://github.com/sigstore/cosign/releases
- 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: License
  name: Apache-2.0
  url: https://github.com/sigstore/cosign/blob/main/LICENSE
- type: AgenticAccess
  url: agentic-access/sigstore-agentic-access.yml
- type: DomainSecurity
  url: security/sigstore-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/
- type: GettingStarted
  url: https://docs.sigstore.dev/quickstart/quickstart-cosign/
- type: GitHubOrganization
  url: https://github.com/sigstore
- type: Blog
  url: https://blog.sigstore.dev/
- type: Community
  url: https://sigstore.dev/community/
- type: Policy Controller
  url: https://docs.sigstore.dev/policy-controller/overview/
- type: Security
  url: https://docs.sigstore.dev/about/security/
- type: Vocabulary
  url: https://raw.githubusercontent.com/api-evangelist/sigstore/refs/heads/main/vocabulary/sigstore-vocabulary.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

Sigstore API — frequently asked questions

Does Sigstore have an API?

Yes. APIs.io lists 6 APIs from Sigstore, including Cosign, Sigstore CA API and Sigstore Entries API, and 3 more.

Is there an OpenAPI specification for the Sigstore API?

Yes. APIs.io indexes 5 OpenAPI specifications for Sigstore, each linked for download from this page.

How much does the Sigstore API cost?

APIs.io lists 1 pricing plan for Sigstore, with each plan's price, limits and inclusions under Pricing on this page.

Is the Sigstore API ready for AI agents?

Sigstore has a Kin Score of 33.9 out of 100 (thin) and an Agent Readiness score of 17.2 (agent-aware), scored by API Evangelist on 2026-11-06.

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