ISBNdb

ISBNdb is the world's largest book database REST API providing access to metadata for over 110 million books and publications. Search by ISBN (ISBN-10 or ISBN-13), title, author, publisher, or subject to retrieve up to 19 data points per book including cover images, publication dates, descriptions, and real-time pricing. The API supports bulk lookups of up to 1,000 ISBNs per request on eligible plans.

ISBNdb publishes 8 API contracts indexed on the APIs.io network, including Author API, Books API, Feed API, and 5 more. Tagged areas include Books, ISBN, Publishing, Metadata, and Library.

The ISBNdb catalog on APIs.io includes 1 JSON-LD context and 1 Spectral governance ruleset.

ISBNdb’s developer surface includes authentication, documentation, pricing, engineering blog, and 10 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

30.2/100 thin ▬ flat Agent 20/100 agent aware saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessPaid

2 published contracts

BooksISBNPublishing Metadata Library Bibliography

What this lets a business do 1

Business capabilities this provider's published APIs can perform, derived from its own contracts. Browse all capabilities →

Developer Platform & API Ecosystem Management

BC-4270

Key

GET /key

Kin Score

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

Composite quality — 30.2/100 · thin

Contract Quality 9.7 / 19

Developer Ergonomics 4.3 / 15

Access Clarity 2.8 / 15

Operational Transparency 0.8 / 10

Contract Governance 0.9 / 9

Discoverability 5.0 / 8

Regulatory Posture 2.5 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 20/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 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 0 / 3

MCP Tool Quality 6 / 6

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.

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 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% 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
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
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document

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 18.4 — up to +16.3 composite points
Developer Ergonomics scores 28.6 — up to +14.3 composite points
Operational Transparency scores 7.9 — up to +12.0 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/isbndb/apis.yml: open an issue on github.com/api-evangelist/isbndb 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
Book Publishing (ONIX / ISBN / EPUB supply chain)	standard	17.2 (thin)	-	-
APIs.guru OpenAPI Directory (API definition directory)	standard	17.2 (thin)	-	-

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 8

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

ISBNdb Author API

Author endpoints

ISBNdb Books API

Book endpoints

ISBNdb Feed API

Feed endpoints for incremental sync

ISBNdb Key API

API key management

ISBNdb Publisher API

Publisher endpoints

ISBNdb Search API

Legacy search endpoints (deprecated)

ISBNdb Stats API

Database statistics

ISBNdb Subject API

Subject endpoints

Scroll for all 8

Open Collections 8

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

ISBNdb API v2 Author API

OPEN COLLECTION

ISBNdb API v2 Books API

OPEN COLLECTION

ISBNdb API v2 Feed API

OPEN COLLECTION

ISBNdb API v2 Key API

OPEN COLLECTION

ISBNdb API v2 Publisher API

OPEN COLLECTION

ISBNdb API v2 Search API

OPEN COLLECTION

ISBNdb API v2 Stats API

OPEN COLLECTION

ISBNdb API v2 Subject API

OPEN COLLECTION

Scroll for all 8

ISBNdb API pricing

Not yet checked against ISBNdb's own pricing page. Compiled by API Evangelist; confirm before you rely on a figure.

Plan	Price
Basic	$14.99
Academic	$14.99
Premium	$35.99
Pro	$99.99
Enterprise	$299.99

Plan details, limits and sources →

Rate limits

: second
: day
: second

Compiled by API Evangelist, not yet checked against ISBNdb's documentation. All 10 limits →

Pricing Plans 1

Published pricing tiers and plan structures.

Isbndb Plans Pricing

5 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Isbndb Rate Limits

10 limits

RATE LIMITS

Service Levels 1

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

ISBNdb

SLA

FinOps 1

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

Isbndb Finops

FINOPS

Semantic Vocabularies 1

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

Isbndb Context

2 classes · 32 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

ISBNdb — jsonschema rules

5 rules · 4 warnings 1 info

SPECTRAL

JSON Schema 1

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

Book

25 properties

JSON SCHEMA

Examples 4

Example request and response payloads for these APIs.

Author Details Response

6 fields

EXAMPLE

Book Get Response

1 fields

EXAMPLE

Books Bulk Request

1 fields

EXAMPLE

Books Search Response

3 fields

EXAMPLE

Security Posture 2

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

Isbndb Authentication

apiKey · 1 scheme

SECURITY

Isbndb Domain Security

TLSv1.3 · DMARC

SECURITY

Agentic Access 1

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

Isbndb Agentic Access

16 operations

16 operations · 0 acting

AGENTIC

Resources

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Build 2

SDKs, sample code, and the tooling you integrate with

PostmanCollection

PostmanCollection

PostmanWorkspace

PostmanWorkspace

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 1

Status, limits, changes, and where to get help

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 2

Properties that don't map to a standard resource type

CapabilityMap

CapabilityMap

Source (apis.yml)

aid: isbndb
name: ISBNdb
description: ISBNdb is the world's largest book database REST API providing access to metadata for over 110 million books
  and publications. Search by ISBN (ISBN-10 or ISBN-13), title, author, publisher, or subject to retrieve up to 19 data points
  per book including cover images, publication dates, descriptions, and real-time pricing. The API supports bulk lookups of
  up to 1,000 ISBNs per request on eligible plans.
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: paid
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Paid
  confidence: medium
  source:
  - plans
  - authentication
  - security
  generated: '2026-11-06'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/isbndb.png
url: https://raw.githubusercontent.com/api-evangelist/isbndb/refs/heads/main/apis.yml
created: '2026-06-13'
modified: '2026-06-13'
specificationVersion: '0.23'
tags:
- Books
- ISBN
- Publishing
- Metadata
- Library
- Bibliography
apis:
- aid: isbndb:isbndb-author-api
  name: ISBNdb Author API
  description: Author endpoints
  humanURL: https://isbndb.com/api-documentation
  baseURL: https://api2.isbndb.com
  tags:
  - Author
  properties:
  - type: OpenAPI
    url: openapi/isbndb-author-api-openapi.yml
  - type: Collection
    url: collections/isbndb-author-api.postman_collection.json
  - type: Documentation
    url: https://isbndb.com/api-documentation
  - type: Pricing
    url: https://isbndb.com/isbn-database
- aid: isbndb:isbndb-books-api
  name: ISBNdb Books API
  description: Book endpoints
  humanURL: https://isbndb.com/api-documentation
  baseURL: https://api2.isbndb.com
  tags:
  - Books
  properties:
  - type: OpenAPI
    url: openapi/isbndb-books-api-openapi.yml
  - type: Collection
    url: collections/isbndb-books-api.postman_collection.json
  - type: Documentation
    url: https://isbndb.com/api-documentation
  - type: Pricing
    url: https://isbndb.com/isbn-database
- aid: isbndb:isbndb-feed-api
  name: ISBNdb Feed API
  description: Feed endpoints for incremental sync
  humanURL: https://isbndb.com/api-documentation
  baseURL: https://api2.isbndb.com
  tags:
  - Feed
  properties:
  - type: OpenAPI
    url: openapi/isbndb-feed-api-openapi.yml
  - type: Collection
    url: collections/isbndb-feed-api.postman_collection.json
  - type: Documentation
    url: https://isbndb.com/api-documentation
  - type: Pricing
    url: https://isbndb.com/isbn-database
- aid: isbndb:isbndb-key-api
  name: ISBNdb Key API
  description: API key management
  humanURL: https://isbndb.com/api-documentation
  baseURL: https://api2.isbndb.com
  tags:
  - Key
  properties:
  - type: OpenAPI
    url: openapi/isbndb-key-api-openapi.yml
  - type: Collection
    url: collections/isbndb-key-api.postman_collection.json
  - type: Documentation
    url: https://isbndb.com/api-documentation
  - type: Pricing
    url: https://isbndb.com/isbn-database
- aid: isbndb:isbndb-publisher-api
  name: ISBNdb Publisher API
  description: Publisher endpoints
  humanURL: https://isbndb.com/api-documentation
  baseURL: https://api2.isbndb.com
  tags:
  - Publishers
  tags_raw:
  - Publisher
  properties:
  - type: OpenAPI
    url: openapi/isbndb-publisher-api-openapi.yml
  - type: Collection
    url: collections/isbndb-publisher-api.postman_collection.json
  - type: Documentation
    url: https://isbndb.com/api-documentation
  - type: Pricing
    url: https://isbndb.com/isbn-database
- aid: isbndb:isbndb-search-api
  name: ISBNdb Search API
  description: Legacy search endpoints (deprecated)
  humanURL: https://isbndb.com/api-documentation
  baseURL: https://api2.isbndb.com
  tags:
  - Search
  properties:
  - type: OpenAPI
    url: openapi/isbndb-search-api-openapi.yml
  - type: Collection
    url: collections/isbndb-search-api.postman_collection.json
  - type: Documentation
    url: https://isbndb.com/api-documentation
  - type: Pricing
    url: https://isbndb.com/isbn-database
- aid: isbndb:isbndb-stats-api
  name: ISBNdb Stats API
  description: Database statistics
  humanURL: https://isbndb.com/api-documentation
  baseURL: https://api2.isbndb.com
  tags:
  - Stats
  properties:
  - type: OpenAPI
    url: openapi/isbndb-stats-api-openapi.yml
  - type: Collection
    url: collections/isbndb-stats-api.postman_collection.json
  - type: Documentation
    url: https://isbndb.com/api-documentation
  - type: Pricing
    url: https://isbndb.com/isbn-database
- aid: isbndb:isbndb-subject-api
  name: ISBNdb Subject API
  description: Subject endpoints
  humanURL: https://isbndb.com/api-documentation
  baseURL: https://api2.isbndb.com
  tags:
  - Subject
  properties:
  - type: OpenAPI
    url: openapi/isbndb-subject-api-openapi.yml
  - type: Collection
    url: collections/isbndb-subject-api.postman_collection.json
  - type: Documentation
    url: https://isbndb.com/api-documentation
  - type: Pricing
    url: https://isbndb.com/isbn-database
common:
- type: CapabilityMap
  url: capabilities/isbndb-capability-edges.yml
  name: ISBNdb Business Capability Map
- type: PostmanCollection
  url: https://www.postman.com/api-evangelist/isbndb/collection/86oo60r/isbndb-api
- type: PostmanWorkspace
  url: https://www.postman.com/api-evangelist/isbndb
- type: AgenticAccess
  url: agentic-access/isbndb-agentic-access.yml
- type: DomainSecurity
  url: security/isbndb-domain-security.yml
- type: Authentication
  url: authentication/isbndb-authentication.yml
- type: Website
  url: https://isbndb.com
- type: Documentation
  url: https://isbndb.com/api-documentation
- type: Pricing
  url: https://isbndb.com/isbn-database
- type: Blog
  url: https://isbndb.com/blog/
- type: X
  url: https://x.com/ISBNdb_com
- type: Plans
  url: plans/isbndb-plans-pricing.yml
- type: RateLimits
  url: rate-limits/isbndb-rate-limits.yml
- type: FinOps
  url: finops/isbndb-finops.yml
X-Provenance:
- date: '2026-08-13'
  surface: OpenAPI
  url: https://api2.isbndb.com/doc.json
  http_status: 200
  action: re-harvested
  note: 'ISBNdb wrote in asking us to update the Postman collection: it documented a dewey_decimal field they do not have,
    and its sample responses were generated placeholders. Both correct. Re-harvested their live spec, which their own docs
    link as the specification of record. Their current spec and the copy we held are BOTH labelled version 2.7.0 with the
    same 16 paths, but theirs has dropped dewey_decimal and added 7 filter schemas — the version string did not change, so
    nothing downstream could detect the revision. dewey_decimal removed from the OpenAPIs, collections, JSON Schema, JSON-LD
    context, vocabulary and examples. Placeholder responses persist because their spec carries exactly one `example` and zero
    `examples`; that fix belongs upstream.'
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

ISBNdb API — frequently asked questions

Does ISBNdb have an API?

Yes. APIs.io lists 8 APIs from ISBNdb, including ISBNdb Author API, ISBNdb Books API and ISBNdb Feed API, and 5 more.

Is there an OpenAPI specification for the ISBNdb API?

Yes. APIs.io indexes 8 OpenAPI specifications for ISBNdb, each linked for download from this page.

How do I authenticate with the ISBNdb API?

ISBNdb uses bearer-token authentication (apiKey · 1 scheme). The details are profiled on APIs.io as Isbndb Authentication.

How much does the ISBNdb API cost?

APIs.io lists 5 pricing plans for ISBNdb, with each plan's price, limits and inclusions under Pricing on this page.

Is the ISBNdb API ready for AI agents?

ISBNdb has a Kin Score of 30.2 out of 100 (thin) and an Agent Readiness score of 20.3 (agent-aware), scored by API Evangelist on 2026-11-06.

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