# Evidence402 Search

> Evidence402 Search is a paid API for AI agents from evidence402.onrender.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-12).

Searches for and retrieves structured academic/research data and verifies DOI citations from public web sources, paid per-call via x402 USDC on Base.

## Facts

- Endpoint: POST https://evidence402.onrender.com/api/v1/search?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/evidence402-search-605c6025
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bYe1DvPPVU_NFFdk5ERYr

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 evidence402-search-605c6025 -d '<json body>'
```

Example prompt: Search Evidence402 for peer-reviewed papers on 'mRNA vaccine efficacy in immunocompromised patients' and give me a structured list of what you find — I need to verify the DOIs are real too.

## When to prefer this

Choose this endpoint when you need to verify DOI citations, find academic papers on a topic, or extract structured data from public web pages without setting up a subscription or long-term API key — ideal for pay-as-you-go agent workflows using x402 micropayments on Base. Prefer it over general-purpose scrapers when citation validation is a key requirement.

## Known failure modes

- Query returns empty papers array if no matching results are found
- DOI not resolvable if the identifier is malformed or not indexed
- Public webpage inaccessible if the URL is paywalled or blocked
- Payment failure if USDC balance is insufficient or x402 transaction is rejected
- Timeout if the target webpage is slow or unavailable
- Rate limiting if too many calls are made in quick succession

## How this service works

Read public webpages, extract structured data and verify DOI citations. No buyer API key or subscription. Pay per call with x402 USDC on Base.

## Output

Returns a JSON object containing the service name, a request ID, and a data object with the original query string and an array of papers or structured results found. Each paper entry typically includes title, authors, DOI, and other bibliographic metadata.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {
   "query": "example topic",
   "papers": []
  },
  "service": "Evidence402",
  "requestId": "example-request"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/evidence402-search-605c6025/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from evidence402.onrender.com](https://www.zero.xyz/host/evidence402.onrender.com/llms.txt)