# ClinicalTrials API
> Search the global clinical-trials registry as an API, powered by the U.S. NIH ClinicalTrials.gov database of 500,000+ studies. Find trials by medical condition, intervention or drug, free-text term, location and recruitment status (recruiting, completed, active, terminated and more), with paging across results, or pull a full study by its NCT id. Each record carries the title, overall status, study type and phases, conditions studied, interventions, lead sponsor, enrollment count, start and completion dates, eligibility criteria (sex, age range, healthy-volunteer policy) and the list of participating sites with city and country. Ideal for patient-matching and recruitment tools, pharma and biotech competitive intelligence, medical research dashboards, health portals and academic analysis.

## Authentication
All requests require your oanor API key in the `x-oanor-key` header. Get one at https://www.oanor.com/developer/keys.

```bash
curl -H "x-oanor-key: oanor_live_…" "https://api.oanor.com/clinicaltrials-api/..."
```

## Pricing
- **Free** (Free) — 3,500 calls/Mo, 2 req/s
- **Starter** ($8/Mo) — 55,000 calls/Mo, 8 req/s
- **Pro** ($22/Mo) — 280,000 calls/Mo, 20 req/s
- **Mega** ($55/Mo) — 1,400,000 calls/Mo, 50 req/s

## Endpoints

### Studies

#### `GET /v1/search` — Search clinical studies

**Parameters:**
- `condition` (query, optional, string) — Medical condition, e.g. diabetes Example: `diabetes`
- `term` (query, optional, string) — Free-text query across all fields
- `intervention` (query, optional, string) — Intervention or drug, e.g. metformin
- `location` (query, optional, string) — Location, e.g. Boston
- `status` (query, optional, string) — RECRUITING | COMPLETED | ACTIVE_NOT_RECRUITING | TERMINATED | … Example: `RECRUITING`
- `page_size` (query, optional, string) — Results per page (1-50, default 10) Example: `10`
- `page_token` (query, optional, string) — Token from a previous response for the next page

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/clinicaltrials-api/v1/search?condition=diabetes&status=RECRUITING&page_size=10"
```

**Response:**
```json
{
    "data": {
        "count": 10,
        "total": 1975,
        "studies": [
            {
                "url": "https://clinicaltrials.gov/study/NCT07361640",
                "title": "DiaMester Pilot RCT: E-health Lifestyle Program for Type 2 Diabetes",
                "nct_id": "NCT07361640",
                "phases": [
                    "NA"
                ],
                "status": "RECRUITING",
                "sponsor": "Oslo University Hospital",
                "conditions": [
                    "Diabetes Mellitus, Type 2"
                ],
                "enrollment": 99,
                "start_date": "2026-01-14",
                "study_type": "INTERVENTIONAL",
                "completion_date": "2027-12"
            },
            {
                "url": "https://clinicaltrials.gov/study/NCT06163482",
                "title": "Hormonal Responses to a Mixed Meal in People With Cystic Fibrosis",
                "nct_id": "NCT06163482",
                "phases": [
                    "EARLY_PHASE1"
                ],
                "status": "RECRUITING",
                "sponsor": "University of Cincinnati",
                "conditions": [
                    "Cystic Fibrosis"
                ],
                "enrollment": 61,
                "start_date": "2023-03-28",
                "study_type": "INTERVENTIONAL",
                "completion_date": "2026-12-30"
            },
            {
                "url": "https://clinicaltrials.gov/study
…(truncated, see openapi.json for full schema)
```

#### `GET /v1/study` — A full study by NCT id

**Parameters:**
- `id` (query, required, string) — NCT number, e.g. NCT00841061 Example: `NCT00841061`

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/clinicaltrials-api/v1/study?id=NCT00841061"
```

**Response:**
```json
{
    "data": {
        "study": {
            "url": "https://clinicaltrials.gov/study/NCT00841061",
            "title": "Cereals as a Source of Iron for Breastfed Infants",
            "nct_id": "NCT00841061",
            "phases": [
                "NA"
            ],
            "status": "COMPLETED",
            "sponsor": "National Institutes of Health (NIH)",
            "locations": [
                {
                    "city": "Iowa City",
                    "state": "Iowa",
                    "country": "United States",
                    "facility": "University of Iowa"
                }
            ],
            "conditions": [
                "Iron Deficiency"
            ],
            "enrollment": 111,
            "start_date": "2003-07",
            "study_type": "INTERVENTIONAL",
            "eligibility": {
                "sex": "ALL",
                "criteria": "Inclusion Criteria: * exclusively breastfed * birth weight between 2500 and 4200g * gestational age \\>36 weeks Exclusion Criteria: * supplementing formula * no iron drops",
                "maximum_age": "1 Year",
                "minimum_age": "28 Days",
                "healthy_volunteers": true
            },
            "brief_summary": "The purpose of this research study is to determine whether the type of iron in infant cereals makes a differance in how well the cereal helps infants remain free of iron deficiency.",
            "interventions": [
                {
                  
…(truncated, see openapi.json for full schema)
```

### Meta

#### `GET /v1/meta` — Statuses & usage notes

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/clinicaltrials-api/v1/meta"
```

**Response:**
```json
{
    "data": {
        "note": "Clinical studies. /v1/search = search by condition=, term=, intervention=, location= and status= (RECRUITING, COMPLETED, …), with page_size and page_token paging (next_page_token returned); /v1/study = a full study by NCT id (e.g. id=NCT00841061) with conditions, interventions, phases, sponsor, eligibility and sites. Data from the U.S. NIH ClinicalTrials.gov registry.",
        "source": "ClinicalTrials.gov v2 API",
        "statuses": [
            "RECRUITING",
            "NOT_YET_RECRUITING",
            "ENROLLING_BY_INVITATION",
            "ACTIVE_NOT_RECRUITING",
            "COMPLETED",
            "SUSPENDED",
            "TERMINATED",
            "WITHDRAWN",
            "AVAILABLE",
            "NO_LONGER_AVAILABLE",
            "UNKNOWN"
        ],
        "endpoints": [
            "/v1/search",
            "/v1/study",
            "/v1/meta"
        ]
    },
    "meta": {
        "timestamp": "2026-06-01T00:04:35.955Z",
        "request_id": "d04a15f3-83ce-4203-a043-4e0236252bd4"
    },
    "status": "ok",
    "message": "Meta retrieved",
    "success": true
}
```


---
Marketplace page: https://www.oanor.com/api/clinicaltrials-api
OpenAPI spec: https://www.oanor.com/api/clinicaltrials-api/openapi.json