# ClinicalTrials.gov Studies Search API

> ClinicalTrials.gov Studies Search API is a paid API for AI agents from project-api-gamma-sable.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-11).

Searches ClinicalTrials.gov for clinical studies matching a keyword term, returning slim JSON results with UI links, paid via USDC on Base.

## Facts

- Endpoint: GET https://project-api-gamma-sable.vercel.app/paid/clinicaltrials/studies?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/clinicaltrials-gov-studies-search-api-ea01d6c9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jSOPVs6QcGMiZqtaTAc24

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability clinicaltrials-gov-studies-search-api-ea01d6c9
```

Example prompt: Search ClinicalTrials.gov for studies on type 2 diabetes and return up to 10 results.

## When to prefer this

Choose this endpoint when you need programmatic, pay-per-query access to ClinicalTrials.gov study data without setting up your own API integration, especially in agent workflows where microtransaction payments via USDC on Base are already supported. Prefer this over direct ClinicalTrials.gov API calls when you want a simplified, slim JSON response with UI links and don't need the full raw API payload.

## Known failure modes

- HTTP 402 if payment is not provided or fails — requires USDC on Base via x402 protocol
- Empty items array if no studies match the search term
- Missing or invalid 'term' query parameter returns an error
- Invalid pageToken may return empty or incorrect page of results
- Network or upstream ClinicalTrials.gov API unavailability

## How this service works

Paid public-data feeds. Unpaid requests return HTTP 402. Prices are USDC on Base.

## Output

Returns a slim JSON array of matching ClinicalTrials.gov study records for the given search term, including basic study metadata and a direct UI link to each study on ClinicalTrials.gov. Supports pagination via a page token.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "term"
     ],
     "properties": {
      "term": {
       "type": "string",
       "description": "Search term"
      },
      "limit": {
       "type": "string",
       "description": "Max results"
      },
      "pageToken": {
       "type": "string",
       "description": "Query param: pageToken"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "what": "ClinicalTrials.gov studies search (slim JSON + uiLink)",
  "items": [],
  "source": "/paid/clinicaltrials/studies"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/clinicaltrials-gov-studies-search-api-ea01d6c9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from project-api-gamma-sable.vercel.app](https://www.zero.xyz/host/project-api-gamma-sable.vercel.app/llms.txt)