ClinicalTrials.gov
ClinicalTrials.gov is the U.S. National Institutes of Health (NIH) registry and results database of publicly and privately supported clinical studies of human participants conducted around the world. Operated by the National Library of Medicine (NLM), it provides a modern REST API (data-api v2) that returns study records, study metadata, search areas, and field definitions in JSON. The predecessor classic API remains available for legacy consumers but is being phased out in favor of the v2 API. Data is in the public domain and freely accessible without authentication.
Real signal across most facets with visible, nameable gaps — the contract exists but is thin, or the portal is good while governance and commercial terms are absent.
API Evangelist profiles ClinicalTrials.gov the way a machine reads it — 19 machine-readable artifacts across 1 API, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — ClinicalTrials.gov scores 40.8/100 (developing), with a separate agent-readiness read of 27/100 (agent aware). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance. Every facet and dimension name is a link: it opens that measurement's page on APIs.io, where the rating runs across the whole catalog — the exact checks that feed it, how every profiled provider distributes on it, and who is at the top of it.
Kin Score
How this is scored →scored 2026-09-08 · rubric v0.20.0
Put this on your own site. The badge is drawn live from ClinicalTrials.gov's current Kin Score — paste it once and it updates itself every time the score is recomputed. It follows your visitor's light or dark setting, and it links back here so anyone who sees it can read the full breakdown.
<!-- Kin Score · API Evangelist -->
<a href="https://providers.apievangelist.com/providers/clinical-trials-gov/"
title="ClinicalTrials.gov on API Evangelist — API profile and Kin Score">
<img src="https://apis.io/badge/clinical-trials-gov.svg"
alt="ClinicalTrials.gov Kin Score — API readiness rating by API Evangelist" width="150" height="150" loading="lazy">
</a>[](https://providers.apievangelist.com/providers/clinical-trials-gov/)<!-- Kin Score · API Evangelist -->
<a href="https://providers.apievangelist.com/providers/clinical-trials-gov/"
title="ClinicalTrials.gov on API Evangelist — API profile and Kin Score">
<img src="https://apis.io/badge/clinical-trials-gov/card.svg"
alt="ClinicalTrials.gov Kin Score — API readiness rating by API Evangelist" width="340" height="120" loading="lazy">
</a>More shapes, themes and sizes → · Score as JSON · How badges work
How we profile ClinicalTrials.gov
Each block below is one kind of artifact we hold for ClinicalTrials.gov. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 6
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
Individual APIs this provider publishes, each with its own machine-readable definition.
ClinicalTrials.gov Classic API
RETIRED. The Classic API was withdrawn in June 2024 and its endpoints now return HTTP 404 (probed 2026-09-06: /api/query/full_studies and /api/info/data_vrs both 404). It is ret...
ClinicalTrials.gov Bulk Downloads
ClinicalTrials.gov provides bulk CSV and JSON downloads of the full study registry through the data-api download endpoints. These artifacts support large-scale analytics, archiv...
AACT Database
AACT (Aggregate Analysis of ClinicalTrials.gov) is a publicly available relational database of all ClinicalTrials.gov study content maintained by the Clinical Trials Transformat...
ClinicalTrials.gov Stats API
The Stats API from ClinicalTrials.gov — 3 operation(s) for stats.
ClinicalTrials.gov Studies API
The Studies API from ClinicalTrials.gov — 5 operation(s) for studies.
ClinicalTrials.gov Version API
The Version API from ClinicalTrials.gov — 1 operation(s) for version.
Open Collections 5
Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.
Open, tool-agnostic API collections (OpenAPI-derived and Bruno).
API Collection
OPEN COLLECTIONClinicalTrials.gov Data API v2 Stats API
OPEN COLLECTIONClinicalTrials.gov Data API v2 Stats Studies API
OPEN COLLECTIONClinicalTrials.gov Data API v2 Stats Version API
OPEN COLLECTIONClinicalTrials.gov Data API v2
OPEN COLLECTIONMCP Servers 1
Model Context Protocol servers expose these APIs directly to AI agents. We profile them because agent-native access is the fastest-growing way this provider's capabilities actually get used.
Model Context Protocol servers that expose these APIs to AI agents.
ClinicalTrials.gov Data API v2 (candidate MCP surface)
A CANDIDATE tool list derived from the ClinicalTrials.gov Data API v2 OpenAPI operations. The National Library of Medicine does not publish an MCP server for ClinicalTrials.gov ...
MCP SERVERPricing Plans 1
Pricing is part of the interface. Machine-readable plans tell you what a tier costs and includes before you commit — one of the things the Kin Score reads for access clarity — renamed from commercial clarity in rubric 0.12, because a free statutory interface has access terms and no commercial ones.
Published pricing tiers and plan structures.
Rate Limits 1
Rate limits are the difference between a demo that works and a production integration that doesn't fall over. Publishing them is an operational-transparency signal — and a hard requirement for any agent that plans its own throughput.
Documented rate limits and quota policies.
Clinical Trials Gov Rate Limits
RATE LIMITSSemantic Vocabularies 1
JSON-LD contexts give the data shared meaning across APIs. We profile them because semantics are what let a machine reconcile 'customer' here with 'customer' somewhere else.
JSON-LD contexts and semantic vocabularies used across these APIs.
Clinical Trials Gov Context
JSON-LDSpectral Rules 1
Governance rulesets we run against this provider's specs — the automated checks behind parts of the score. Profiling them makes the quality bar explicit and re-runnable, not a matter of opinion.
ClinicalTrials.gov API Rules
SPECTRALSecurity Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Agentic Access 1
An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.
Recommended x-agentic-access execution contracts for AI agents.
Resources
Every other property we hold for ClinicalTrials.gov — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Get Started 2
Portal, sign-up, and the first successful call
Documentation 2
Reference material describing how the API behaves
Agent Surfaces 3
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 7
Pagination, idempotency, versioning, errors, and events
Scroll within the panel for all 7 ·
Build 1
SDKs, sample code, and the tooling you integrate with
Access & Security 2
Authentication, authorization, and security posture
Operate 7
Status, limits, changes, and where to get help
Scroll within the panel for all 7 ·
Commercial 3
Pricing, plans, and the legal terms of use
Company 3
The organization behind the API
Other 1
Properties that don't map to a standard resource type
← All providers · Data indexed from github.com/api-evangelist/clinical-trials-gov · machine-readable index on apis.io
This is an independent, third-party profile of ClinicalTrials.gov, published by API Evangelist. We do not operate, host, resell, or support these APIs, and we are not affiliated with or endorsed by the company unless stated above. Everything here is built from publicly available information — the company's own site, developer portal, documentation, public repositories, and the specifications it publishes for public use. Nothing is obtained by breaching a system, defeating an access control, or using credentials.
The Kin Score and Agent Readiness rating are independently calculated assessments of a company's public API artifacts, scored against a published rubric. They are not certifications, endorsements, security assessments, or audits.
Corrections, re-scores, and removal are free — no partnership or purchase required, and you do not need to justify the request. A removed company is recorded as unrated, never scored zero for having asked. Acknowledgement within one business day; removal within two.
info@apievangelist.com
·
Read the full data-sourcing policy →
On a security or compliance team? Put security in the subject line and
you will get a person, not a form — we will tell you exactly which public URLs this profile was built from.