Project Gutenberg

Project Gutenberg is a free ebook library providing access to over 75,000 public domain books via the Gutendex REST API. The API enables developers to search and retrieve bibliographic metadata for books and authors, filter by language, copyright status, topic, and MIME type, and access download links for multiple formats including EPUB, Kindle, HTML, and plain text. Project Gutenberg has pioneered free ebooks since 1971 and the Gutendex API makes its catalog programmatically accessible via a simple JSON REST interface with no authentication required.

Project Gutenberg publishes 1 API on the APIs.io network: Gutendex API. Tagged areas include Books, Ebooks, Public Domain, Literature, and Library.

Project Gutenberg’s developer surface includes documentation, engineering blog, pricing, and 8 more developer resources.

🌐 Visit website 📡 Source on GitHub

28.5/100 thin ▬ flat Agent 18/100 agent aware Full breakdown ↓
scored 2026-08-21 · rubric v0.12.0

AccessFreeOpen⚡ Free to try

1 APIs

Books Ebooks Public Domain Literature Library MetadataEPUB

Kin Score

Kin Score How this is scored →
scored 2026-08-21 · rubric v0.12.0

Composite quality — 28.5/100 · thin

Contract Quality 6.0 / 21

Developer Ergonomics 2.0 / 17

Access Clarity 6.7 / 17

Operational Transparency 5.8 / 11

Contract Governance 0.0 / 10

Discoverability 5.8 / 9

Regulatory Posture 1.7 / 15

Agent readiness — 18/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 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

Regulatory Posture applies to this provider. Its tags matched the Education & Research 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.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/gutenberg: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 1

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

Rate Limits 1

Documented rate limits and quota policies.

Gutenberg Rate Limits

3 limits

RATE LIMITS

FinOps 1

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

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrg

GitHubOrg

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Operate 2

Status, limits, changes, and where to get help

StatusPage

StatusPage

RateLimits

RateLimits

Commercial 3

Pricing, plans, and the legal terms of use

Pricing

Pricing

Plans

Plans

FinOps

FinOps

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Source (apis.yml)

aid: gutenberg
name: Project Gutenberg
description: Project Gutenberg is a free ebook library providing access to over 75,000 public domain books via the Gutendex
  REST API. The API enables developers to search and retrieve bibliographic metadata for books and authors, filter by language,
  copyright status, topic, and MIME type, and access download links for multiple formats including EPUB, Kindle, HTML, and
  plain text. Project Gutenberg has pioneered free ebooks since 1971 and the Gutendex API makes its catalog programmatically
  accessible via a simple JSON REST interface with no authentication required.
accessModel:
  pricing: free
  onboarding: open
  trial: false
  try_now: true
  public: true
  label: Free · Open access
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/gutenberg.png
url: https://raw.githubusercontent.com/api-evangelist/gutenberg/refs/heads/main/apis.yml
created: '2026-06-13'
modified: '2026-06-13'
specificationVersion: '0.23'
tags:
- Books
- Ebooks
- Public Domain
- Literature
- Library
- Metadata
- EPUB
apis:
- aid: gutenberg:gutendex
  name: Gutendex API
  description: Gutendex is a JSON web API for Project Gutenberg ebook metadata. It provides access to the catalog of 75,000+
    public domain books with filtering by language, copyright status, topic, author lifespan, and MIME type. The API returns
    paginated JSON results including book titles, authors, subjects, bookshelves, download formats, and download counts. No
    authentication or API key is required.
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  humanURL: https://gutendex.com/
  baseURL: https://gutendex.com
  tags:
  - Books
  - Ebooks
  - Public Domain
  - Metadata
  - Literature
  properties:
  - type: Documentation
    url: https://gutendex.com/
  - type: OpenAPI
    url: https://gutendex.com/books
common:
- type: DomainSecurity
  url: security/gutenberg-domain-security.yml
- type: Website
  url: https://www.gutenberg.org/
- type: Documentation
  url: https://gutendex.com/
- type: GitHubOrg
  url: https://github.com/gutenbergtools
- type: Blog
  url: https://www.gutenberg.org/help/
- type: Pricing
  url: https://gutendex.com/
- type: StatusPage
  url: https://www.gutenberg.org/
- type: X
  url: https://twitter.com/gutenberg_org
- type: Plans
  url: plans/gutenberg-plans-pricing.yml
- type: RateLimits
  url: rate-limits/gutenberg-rate-limits.yml
- type: FinOps
  url: finops/gutenberg-finops.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

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