# AttestPage: Web Page Quote & Citation Verifier

> AttestPage: Web Page Quote & Citation Verifier is a paid API for AI agents from vehcdj664efetfrsolne5umanq.srv.us, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-17).

Creates a signed cryptographic attestation (receipt) proving whether a specific SHA-256-hashed content was observed on a live web page at a given moment, enabling quote and citation verification for AI agents.

## Facts

- Endpoint: POST https://vehcdj664efetfrsolne5umanq.srv.us/v1/attest?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-17
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/attestpage-web-page-quote-citation-verifier-4fda376a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_EYmeDdMKVcmkul781Vjo9

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 attestpage-web-page-quote-citation-verifier-4fda376a -d '<json body>'
```

Example prompt: Can you get a signed attestation proving whether the SHA-256 hash e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 appears in the content of that web page, and include a note 'checked for blog post audit'?

## When to prefer this

Choose this endpoint when you need cryptographically signed, tamper-evident proof that specific content (identified by SHA-256) was observed on a live web page — particularly for AI agent fact-checking pipelines, legal/compliance evidence collection, journalism verification workflows, or any scenario where 'trust but verify' is insufficient and you need a verifiable audit trail. Unlike a simple page scrape, this returns a signed receipt suitable for third-party verification.

## Known failure modes

- 400 if an idempotency_key is provided on a non-x402 (trial/L402) call
- 409 if the same idempotency_key is reused with a different SHA-256 hash
- Invalid SHA-256 format (must be 64 hex characters) causes schema validation failure
- Payment failure via x402 protocol blocks attestation creation
- Network timeout if the target page is slow or unavailable

## How this service works

Signed evidence about web pages, for AI agents. Ask whether a quote appears on a page or check every citation in an answer at once, fetch a page and learn…

## Output

A JSON object containing a signed JWT receipt (the 'receipt' field), the attestation tier, and an attestation object with a sequence number, the SHA-256 that was attested, the issued_at timestamp, a first_seen boolean indicating if this hash was seen for the first time, and optional note_sha256 and idempotency_key_sha256 fields. The receipt can be stored and later presented as cryptographic evidence.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "note": {
   "type": "string",
   "maxLength": 280,
   "description": "Optional note; only its SHA-256 goes in the receipt."
  },
  "sha256": {
   "type": "string",
   "pattern": "^[0-9a-fA-F]{64}$",
   "description": "SHA-256 (hex) of the thing being attested."
  },
  "idempotency_key": {
   "type": "string",
   "maxLength": 128,
   "description": "Optional, x402 payments only (keys are scoped to the paying address; trial and L402 calls get 400). Retries with the same key and sha256 get the same attestation (the receipt names that call own payment tx); a different sha256 gets 409."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "tier": "paid",
  "receipt": "eyJ…",
  "attestation": {
   "seq": 1042,
   "sha256": "e3b0…",
   "issued_at": "2026-10-09T12:00:00Z",
   "first_seen": true,
   "note_sha256": "…",
   "idempotency_key": null,
   "idempotency_key_sha256": null
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/attestpage-web-page-quote-citation-verifier-4fda376a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from vehcdj664efetfrsolne5umanq.srv.us](https://www.zero.xyz/host/vehcdj664efetfrsolne5umanq.srv.us/llms.txt)