# agentshelf.syntexa.ch Citation DOI Extractor

> agentshelf.syntexa.ch Citation DOI Extractor is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-02).

Extracts a citation DOI from a public web page or raw HTML content, with SSRF protection.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/profile-citation-doi?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agentshelf-syntexa-ch-citation-doi-extractor-b713e0ef
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_6EInP7tBq-zqMdG8S2qbK

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 agentshelf-syntexa-ch-citation-doi-extractor-b713e0ef -d '<json body>'
```

Example prompt: Can you extract the DOI from this journal article page? The URL is https://www.nature.com/articles/s41586-023-06555-x

## When to prefer this

Use this endpoint when you need to reliably extract a DOI from an academic or scientific web page by URL or raw HTML, especially in an automated pipeline where SSRF safety is required. Prefer this over general-purpose scrapers when the target entity is specifically a citation DOI. Use the free sandbox endpoint (/v1/sandbox/profile-citation-doi) first to validate before paying $0.01 USDC per call.

## Known failure modes

- No DOI found on the page or in the HTML — returns empty or null result
- URL points to a private/internal IP (SSRF blocked) — request rejected
- URL is unreachable or returns non-200 status — fetch failure
- HTML exceeds 200,000 character limit — input too large
- Malformed or missing input (neither url nor html provided) — validation error
- DOI embedded in non-standard formats may not be detected

## How this service works

Call when an agent needs citation_doi extracted from a public page or HTML (SSRF-safe). Exact $0.01 USDC. Prefer unpaid POST /v1/sandbox/profile-citation-doi first.

## Output

Returns the extracted citation DOI (digital object identifier) found within the provided URL's page content or the supplied raw HTML, typically as a string value like '10.xxxx/yyyyy'.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "maxLength": 2048,
   "minLength": 8,
   "description": "Public page to fetch. The selector or profile is fixed by the SKU. Provide url or html."
  },
  "html": {
   "type": "string",
   "examples": [
    "<!doctype html><html lang=\"en\"><head><title>Hello</title>\n<meta name=\"description\" content=\"Desc\"><meta property=\"og:title\" content=\"OG\">\n<link rel=\"canonical\" href=\"https://example.com/\"><link rel=\"icon\" href=\"/favicon.ico\">\n</head><body><h1>Hello</h1><a href=\"https://example.com/a\">A</a></body></html>"
   ],
   "maxLength": 200000,
   "minLength": 1,
   "description": "HTML to extract from locally. Provide html or url. When both are set, html is used."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agentshelf-syntexa-ch-citation-doi-extractor-b713e0ef/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)