# x402.shizu.me Notarization Service

> x402.shizu.me Notarization Service is a paid API for AI agents from x402.shizu.me, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Records a SHA-256 hash of arbitrary data with a timestamp and HMAC receipt, or retrieves when a given hash was first notarized, providing third-party proof of data existence at a point in time.

## Facts

- Endpoint: GET https://x402.shizu.me/notarize
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-shizu-me-notarization-service-cd0c8aac
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__J3dEPQQ6C0hCuxRqpWPz

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 x402-shizu-me-notarization-service-cd0c8aac
```

Example prompt: Can you notarize this text for me — 'Q4 product roadmap draft v1: launch in March' — and give me a timestamped HMAC receipt proving it existed right now?

## When to prefer this

Use this endpoint when you need a cryptographically verifiable, third-party-attested proof that a piece of data existed at a specific moment in time — something an AI agent cannot self-certify. Prefer this over client-side hashing when the timestamp itself needs to be trusted by an external party, e.g. for intellectual property claims, audit trails, or dispute resolution.

## Known failure modes

- Missing or malformed data payload returns an error with no hash or receipt
- Hash not found in GET lookup returns a not-yet-notarized status
- Network or payment failure results in no receipt being issued
- Malformed hash query string returns a validation error
- Server unavailability means timestamp cannot be certified

## How this service works

Prove a piece of data existed at a point in time. POST {data} returns its sha256, a recorded timestamp, and an HMAC receipt; GET ?hash= tells you whether and when that hash was first notarized. An agent can hash data but cannot self-certify WHEN it existed to a third party — this is that proof.

## Output

For POST (notarize): returns the SHA-256 hash of the submitted data, a server-recorded UTC timestamp, and an HMAC receipt that a third party can use to verify the data existed at that moment. For GET with ?hash=: returns whether that hash has been previously notarized and, if so, the earliest recorded timestamp.

## Request schema (JSON Schema)

```json
{
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "properties": {
  "input": {
   "type": "object",
   "properties": {
    "method": {
     "const": "GET"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "hash": {
       "type": "string"
      }
     },
     "required": [
      "hash"
     ]
    }
   },
   "required": [
    "method"
   ]
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ts": 1784300000,
  "alg": "sha256",
  "hash": "9f2b…",
  "receipt": "c1a…",
  "first_seen": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-shizu-me-notarization-service-cd0c8aac/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.shizu.me](https://www.zero.xyz/host/x402.shizu.me/llms.txt)