# Ysaere Notary — Hash Receipt

> Ysaere Notary — Hash Receipt is a paid API for AI agents from api.ysaere.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-13).

Notarizes a document or data payload by creating a cryptographically signed hash receipt for ~$0.02 USDC, returning a signature and a public verification URL.

## Facts

- Endpoint: POST https://api.ysaere.com/v1/notary/receipts
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ysaere-notary-hash-receipt-65d9603b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_al2L3TpZ5qPt2Yhft_pCP

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 ysaere-notary-hash-receipt-65d9603b -d '<json body>'
```

Example prompt: Notarize this contract for me — hash it, sign it, and give me a receipt I can share so anyone can verify its integrity later; I'll pay the $0.02 fee.

## When to prefer this

Choose this endpoint when you need a lightweight, low-cost (~$0.02) cryptographic proof-of-existence for any document, file, or data payload. It is ideal when you want an externally verifiable, signed receipt without storing the original content — only its hash is retained. Prefer it over full KYB or entity classification endpoints when your goal is integrity attestation rather than identity verification. Best for audit trails, timestamping creative or legal work, or producing receipts that third parties can independently verify via the returned verify_url.

## Known failure modes

- Insufficient USDC balance or payment failure — x402 payment not completed, no receipt created
- Malformed or missing content body — 400 error, hash cannot be computed
- Network timeout during signing — partial failure, receipt may not be issued
- Invalid content encoding — the endpoint may reject non-UTF-8 or oversized payloads
- Duplicate notarization of identical content — returns a new receipt each time (not idempotent)

## How this service works

Ysaere Notary — pay ~$0.02 USDC → signed hash_only receipt + verify_url; free GET resolve/proof (integrity, not factual truth).

## Output

Returns a JSON object containing: a signed SHA-512 content hash (v2:sha512:…), a cryptographic signature, a public verify_url where anyone can confirm the receipt, the payment rail used (x402), and the on-chain transaction hash. The receipt proves integrity (that the content was unchanged) but not factual truth of the content itself.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {
   "mode": "hash_only",
   "verified": true,
   "signature": "…",
   "verify_url": "https://api.ysaere.com/v1/notary/receipts/…",
   "content_hash": "v2:sha512:…"
  },
  "usage": {
   "payment_rail": "x402",
   "x402_tx_hash": "0x…",
   "credits_consumed": 0
  },
  "provenance": {
   "kind": "external_attestation",
   "mode": "hash_only",
   "signature": "…",
   "verify_url": "https://api.ysaere.com/v1/notary/receipts/…"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ysaere-notary-hash-receipt-65d9603b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.ysaere.com](https://www.zero.xyz/host/api.ysaere.com/llms.txt)