United States National Library of Medicine

The United States National Library of Medicine (NLM) is the world's largest biomedical library. It serves as a vital resource for researchers, healthcare professionals, and the general public by providing access to a vast collection of biomedical literature and resources. The NLM offers a wide range of services and resources including online databases, digital archives, and research tools that support medical research, education, and patient care. Key APIs include the NCBI E-Utilities (PubMed, Entrez), NCBI Datasets (genomes, genes), BLAST sequence alignment, and the ClinicalTrials.gov API.

United States National Library of Medicine publishes 10 API contracts indexed on the APIs.io network, including Metadata API, Studies API, BLAST API, and 7 more. Tagged areas include Federal Government, Biomedical Research, Healthcare, Genomics, and Literature.

The United States National Library of Medicine catalog on APIs.io includes 1 JSON-LD context and 2 Spectral governance rulesets.

United States National Library of Medicine’s developer surface includes authentication, developer portal, and 11 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

32.2/100 thin ▬ flat Agent 25/100 agent aware Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessFreemiumSelf serve⚡ Free to try

4 published contracts

Federal Government Biomedical Research Healthcare Genomics Literature

What this lets a business do 1

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

Clinical Trials Management

BC-1520

Studies

GET /studies

Kin Score

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

Composite quality — 32.2/100 · thin

Contract Quality 9.6 / 19

Developer Ergonomics 4.7 / 15

Access Clarity 1.2 / 15

Operational Transparency 2.8 / 10

Contract Governance 0.9 / 9

Discoverability 5.4 / 8

Regulatory Posture 2.0 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 25/100 · 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 7 / 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 Health 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
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document
Delegated User Identity +6 pts — a served discovery document listing authorization_code in grant_types_supported (served), else an oauth2 authorizationCode flow or openIdConnect declared in an OpenAPI (documented)

8 more unmet checks in the Agent Readiness table above.

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

Access Clarity scores 7.9 — up to +18.4 composite points
Developer Ergonomics scores 31.0 — up to +13.8 composite points
Contract Quality scores 51.4 — up to +12.2 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/united-states-national-library-of-medicine/apis.yml: open an issue on github.com/api-evangelist/united-states-national-library-of-medicine 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
Life Sciences (Biotech and Pharma R&D)	standard	17.2 (thin)	-	-
US Federal API Programs (api.data.gov, Login.gov, GSA MAS, FedRAMP)	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 10

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

United States National Library of Medicine Metadata API

API metadata and field definitions

United States National Library of Medicine Studies API

Clinical trial study search and retrieval

United States National Library of Medicine BLAST API

BLAST sequence search submission and retrieval

United States National Library of Medicine Fetch API

Retrieve records from Entrez databases

United States National Library of Medicine Gene API

Gene records and sequence data

United States National Library of Medicine Genome API

Genome assembly data and metadata

United States National Library of Medicine Info API

Database information and statistics

United States National Library of Medicine Link API

Find linked records across databases

United States National Library of Medicine Search API

Search Entrez databases

United States National Library of Medicine Taxonomy API

NCBI taxonomy information

Scroll for all 10

Open Collections 14

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

NCBI BLAST URL API

OPEN COLLECTION

NCBI Datasets REST API

OPEN COLLECTION

NCBI E-Utilities API

OPEN COLLECTION

ClinicalTrials.gov API

OPEN COLLECTION

NCBI URL BLAST API

OPEN COLLECTION

NCBI URL BLAST Fetch API

OPEN COLLECTION

NCBI URL BLAST Gene API

OPEN COLLECTION

NCBI URL BLAST Genome API

OPEN COLLECTION

NCBI URL BLAST Info API

OPEN COLLECTION

NCBI URL BLAST Link API

OPEN COLLECTION

NCBI URL BLAST Metadata API

OPEN COLLECTION

NCBI URL BLAST Search API

OPEN COLLECTION

NCBI URL BLAST Studies API

OPEN COLLECTION

NCBI URL BLAST Taxonomy API

OPEN COLLECTION

Scroll for all 14

United States National Library of Medicine API pricing

Not yet checked against United States National Library of Medicine's own pricing page. Compiled by API Evangelist on 2026-05-04; confirm before you rely on a figure. A free plan or tier is listed.

Plan	Price
Free freemium	Free
Professional paid	Free
Enterprise enterprise	—

Plan details, limits and sources →

Rate limits

Free Tier Default: 10 requests per minute
Free Tier Monthly Quota: 1000 requests per month
Professional Tier Default: 100 requests per minute

Compiled by API Evangelist, not yet checked against United States National Library of Medicine's documentation. All 5 limits →

Pricing Plans 1

Published pricing tiers and plan structures.

United States National Library Of Medicine Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

United States National Library Of Medicine Rate Limits

5 limits

RATE LIMITS

Service Levels 1

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

United States National Library of Medicine

SLA

FinOps 1

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

United States National Library Of Medicine Finops

FINOPS

Semantic Vocabularies 1

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

United States National Library Of Medicine Context

4 classes · 19 properties

JSON-LD

Spectral Rules 2

Spectral governance rulesets for linting and validating these APIs.

United States National Library of Medicine — ncbi e utilities rules

7 rules · 3 errors 4 warnings

SPECTRAL

United States National Library of Medicine — jsonschema rules

5 rules · 3 warnings 2 info

SPECTRAL

JSON Schema 2

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

NCBI PubMed Article

12 properties

JSON SCHEMA

ClinicalTrials.gov Study

17 properties

JSON SCHEMA

JSON Structure 1

JSON Structure definitions describing this provider's data shapes.

Ncbi Pubmed Article Structure

0 properties

JSON STRUCTURE

Examples 3

Example request and response payloads for these APIs.

Ncbi Datasets Get Genome Example

3 fields

EXAMPLE

Ncbi Esearch Pubmed Example

3 fields

EXAMPLE

Nlm Clinicaltrials Search Example

3 fields

EXAMPLE

Security Posture 2

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

United States National Library Of Medicine Authentication

apiKey · 1 scheme

SECURITY

United States National Library Of Medicine Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

Agentic Access 1

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

United States National Library Of Medicine Agentic Access

17 operations · 1 acting

AGENTIC

Resources

Get Started 1

Portal, sign-up, and the first successful call

Portal

Portal

Documentation 1

Reference material describing how the API behaves

ContributionGuide

ContributionGuide

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 3

Status, limits, changes, and where to get help

RateLimits

RateLimits

IssueTracker

IssueTracker

Releases

Releases

Commercial 2

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

Company 2

The organization behind the API

Website

Website

LinkedIn

Other 1

Properties that don't map to a standard resource type

CapabilityMap

CapabilityMap

Source (apis.yml)

aid: united-states-national-library-of-medicine
url: https://raw.githubusercontent.com/api-evangelist/united-states-national-library-of-medicine/refs/heads/main/apis.yml
apis:
- aid: united-states-national-library-of-medicine:united-states-national-library-of-medicine-metadata-api
  name: United States National Library of Medicine Metadata API
  description: API metadata and field definitions
  humanURL: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  baseURL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils
  tags:
  - Metadata
  properties:
  - type: OpenAPI
    url: openapi/united-states-national-library-of-medicine-metadata-api-openapi.yml
  - type: Documentation
    url: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  - type: Portal
    url: https://www.ncbi.nlm.nih.gov/home/develop/api/
  - type: SpectralRules
    url: https://raw.githubusercontent.com/api-evangelist/united-states-national-library-of-medicine/refs/heads/main/rules/ncbi-e-utilities-rules.yml
  - type: Documentation
    url: https://www.ncbi.nlm.nih.gov/datasets/docs/v2/api/
  - type: SwaggerUI
    url: https://www.ncbi.nlm.nih.gov/datasets/docs/v2/api/rest-api/
  - type: Repository
    url: https://github.com/ncbi/datasets
  - type: Documentation
    url: https://blast.ncbi.nlm.nih.gov/doc/blast-help/developerinfo.html
  - type: Documentation
    url: https://clinicaltrials.gov/data-api/api
  - type: Portal
    url: https://clinicaltrials.gov/data-api/api#introduction
- aid: united-states-national-library-of-medicine:united-states-national-library-of-medicine-studies-api
  name: United States National Library of Medicine Studies API
  description: Clinical trial study search and retrieval
  humanURL: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  baseURL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils
  tags:
  - Studies
  properties:
  - type: OpenAPI
    url: openapi/united-states-national-library-of-medicine-studies-api-openapi.yml
  - type: Documentation
    url: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  - type: Portal
    url: https://www.ncbi.nlm.nih.gov/home/develop/api/
  - type: SpectralRules
    url: https://raw.githubusercontent.com/api-evangelist/united-states-national-library-of-medicine/refs/heads/main/rules/ncbi-e-utilities-rules.yml
  - type: Documentation
    url: https://www.ncbi.nlm.nih.gov/datasets/docs/v2/api/
  - type: SwaggerUI
    url: https://www.ncbi.nlm.nih.gov/datasets/docs/v2/api/rest-api/
  - type: Repository
    url: https://github.com/ncbi/datasets
  - type: Documentation
    url: https://blast.ncbi.nlm.nih.gov/doc/blast-help/developerinfo.html
  - type: Documentation
    url: https://clinicaltrials.gov/data-api/api
  - type: Portal
    url: https://clinicaltrials.gov/data-api/api#introduction
- aid: united-states-national-library-of-medicine:united-states-national-library-of-medicine-blast-api
  name: United States National Library of Medicine BLAST API
  description: BLAST sequence search submission and retrieval
  humanURL: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  baseURL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils
  tags:
  - BLAST
  properties:
  - type: OpenAPI
    url: openapi/united-states-national-library-of-medicine-blast-api-openapi.yml
- aid: united-states-national-library-of-medicine:united-states-national-library-of-medicine-fetch-api
  name: United States National Library of Medicine Fetch API
  description: Retrieve records from Entrez databases
  humanURL: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  baseURL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils
  tags:
  - Fetch
  properties:
  - type: OpenAPI
    url: openapi/united-states-national-library-of-medicine-fetch-api-openapi.yml
- aid: united-states-national-library-of-medicine:united-states-national-library-of-medicine-gene-api
  name: United States National Library of Medicine Gene API
  description: Gene records and sequence data
  humanURL: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  baseURL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils
  tags:
  - Gene
  properties:
  - type: OpenAPI
    url: openapi/united-states-national-library-of-medicine-gene-api-openapi.yml
- aid: united-states-national-library-of-medicine:united-states-national-library-of-medicine-genome-api
  name: United States National Library of Medicine Genome API
  description: Genome assembly data and metadata
  humanURL: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  baseURL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils
  tags:
  - Genome
  properties:
  - type: OpenAPI
    url: openapi/united-states-national-library-of-medicine-genome-api-openapi.yml
- aid: united-states-national-library-of-medicine:united-states-national-library-of-medicine-info-api
  name: United States National Library of Medicine Info API
  description: Database information and statistics
  humanURL: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  baseURL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils
  tags:
  - Info
  properties:
  - type: OpenAPI
    url: openapi/united-states-national-library-of-medicine-info-api-openapi.yml
- aid: united-states-national-library-of-medicine:united-states-national-library-of-medicine-link-api
  name: United States National Library of Medicine Link API
  description: Find linked records across databases
  humanURL: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  baseURL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils
  tags:
  - Link
  properties:
  - type: OpenAPI
    url: openapi/united-states-national-library-of-medicine-link-api-openapi.yml
- aid: united-states-national-library-of-medicine:united-states-national-library-of-medicine-search-api
  name: United States National Library of Medicine Search API
  description: Search Entrez databases
  humanURL: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  baseURL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils
  tags:
  - Search
  properties:
  - type: OpenAPI
    url: openapi/united-states-national-library-of-medicine-search-api-openapi.yml
- aid: united-states-national-library-of-medicine:united-states-national-library-of-medicine-taxonomy-api
  name: United States National Library of Medicine Taxonomy API
  description: NCBI taxonomy information
  humanURL: https://www.ncbi.nlm.nih.gov/books/NBK25497/
  baseURL: https://eutils.ncbi.nlm.nih.gov/entrez/eutils
  tags:
  - Taxonomy
  properties:
  - type: OpenAPI
    url: openapi/united-states-national-library-of-medicine-taxonomy-api-openapi.yml
name: United States National Library of Medicine
tags:
- Federal Government
- Biomedical Research
- Healthcare
- Genomics
- Literature
tags_raw:
- Federal Government
- Biomedical Research
- Healthcare
- Genomics
- Literature
- Federal-Government
kind: contract
deliveryModel:
  model: unknown
  license_evidence:
    not_product:
    - ncbi/datasets
  open_source: unknown
  commercial: false
  callable_host: true
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - openapi
  - repository-not-product
  generated: '2026-09-25'
  method: derived
accessModel:
  pricing: freemium
  onboarding: self-serve
  trial: false
  try_now: true
  public: false
  gated: none
  gated_source:
  - onboarding
  label: Freemium · Self-serve signup
  confidence: medium
  source:
  - plans
  - authentication
  - security
  generated: '2026-11-06'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/united-states-national-library-of-medicine.png
common:
- type: Plans
  url: plans/united-states-national-library-of-medicine-plans-pricing.yml
- type: RateLimits
  url: rate-limits/united-states-national-library-of-medicine-rate-limits.yml
- type: FinOps
  url: finops/united-states-national-library-of-medicine-finops.yml
- type: Website
  url: https://www.nlm.nih.gov/
- type: CapabilityMap
  url: capabilities/united-states-national-library-of-medicine-capability-edges.yml
  name: United States National Library of Medicine Business Capability Map
- type: IssueTracker
  url: https://github.com/ncbi/datasets/issues
- type: Releases
  url: https://github.com/ncbi/datasets/releases
- type: ContributionGuide
  url: https://github.com/ncbi/datasets/blob/master/CONTRIBUTING.md
- type: AgenticAccess
  url: agentic-access/united-states-national-library-of-medicine-agentic-access.yml
- type: DomainSecurity
  url: security/united-states-national-library-of-medicine-domain-security.yml
- type: Authentication
  url: authentication/united-states-national-library-of-medicine-authentication.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/national-library-of-medicine-nlm
- url: https://www.ncbi.nlm.nih.gov/home/develop/api/
  type: Portal
created: 2024/01/01
modified: '2026-05-19'
position: Consuming
access: 3rd-Party
description: The United States National Library of Medicine (NLM) is the world's largest biomedical library. It serves as
  a vital resource for researchers, healthcare professionals, and the general public by providing access to a vast collection
  of biomedical literature and resources. The NLM offers a wide range of services and resources including online databases,
  digital archives, and research tools that support medical research, education, and patient care. Key APIs include the NCBI
  E-Utilities (PubMed, Entrez), NCBI Datasets (genomes, genes), BLAST sequence alignment, and the ClinicalTrials.gov API.
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
specificationVersion: '0.23'
x-parent: nih

United States National Library of Medicine API — frequently asked questions

Does United States National Library of Medicine have an API?

Yes. APIs.io lists 10 APIs from United States National Library of Medicine, including United States National Library of Medicine Metadata API, United States National Library of Medicine Studies API and United States National Library of Medicine BLAST API, and 7 more.

Is there an OpenAPI specification for the United States National Library of Medicine API?

Yes. APIs.io indexes 10 OpenAPI specifications for United States National Library of Medicine, each linked for download from this page.

How do I authenticate with the United States National Library of Medicine API?

United States National Library of Medicine uses bearer-token authentication (apiKey · 1 scheme). The details are profiled on APIs.io as United States National Library Of Medicine Authentication.

How much does the United States National Library of Medicine API cost?

APIs.io lists 3 pricing plans for United States National Library of Medicine, with each plan's price, limits and inclusions under Pricing on this page.

Is the United States National Library of Medicine API ready for AI agents?

United States National Library of Medicine has a Kin Score of 32.2 out of 100 (thin) and an Agent Readiness score of 24.6 (agent-aware), scored by API Evangelist on 2026-11-06.

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get_provider_artifactsEvery artifact this provider publishes, grouped by type.
get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

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