# Genexxis Notary Stamp

> Genexxis Notary Stamp is a paid API for AI agents from notary.genexxis.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-29).

Timestamps a SHA-256 hash and returns a cryptographically signed receipt proving the hash existed at a specific moment in time.

## Facts

- Endpoint: POST https://notary.genexxis.com/stamp?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/genexxis-notary-stamp-02b9ad4b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_M7XoSx4I28Wf4i8Nhe9Kd

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 genexxis-notary-stamp-02b9ad4b -d '<json body>'
```

Example prompt: Please notarize this SHA-256 hash — 1a19868d3b6b3f57f523b3202b9ae40155dc1491b3727c608f573acc615d9a0c — and label it 'contract-final-v2' so I have a signed, timestamped receipt proving it existed right now.

## When to prefer this

Choose this endpoint when you need a lightweight, cryptographically signed proof-of-existence for a document or file hash without requiring a full blockchain transaction. It is ideal for compliance workflows, legal timestamping, intellectual property protection, and audit trails where a server-signed receipt is sufficient. Prefer this over blockchain anchoring when cost, latency, or simplicity are priorities, and the trust anchor of a known server key is acceptable.

## Known failure modes

- Invalid hash format (not 64 hex chars) returns a 400 error
- Hash with invalid characters or wrong length rejected
- Label exceeding 120 characters or containing pipe character rejected
- Payment failure or insufficient USDC balance returns 402
- Server signing key unavailable returns 500
- Duplicate hash submission creates a new independent receipt (not idempotent)

## How this service works

Timestamp a SHA-256 hash: returns a stored, server-signed receipt (id, hash, label, timestamp, signer, message, signature, verify URL) proving the hash was presented at that time.

## Output

A JSON receipt containing: a unique record ID (UUID), the submitted hash, the optional label, the server's signer Ethereum address, an ISO 8601 timestamp of when the hash was presented, a structured signed message string, a 65-byte cryptographic signature over that message, and a verifyUrl pointing to the endpoint where the receipt can be independently verified.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "hash": {
   "type": "string",
   "description": "SHA-256 digest of your document, 64 hex chars, optional 0x prefix"
  },
  "label": {
   "type": "string",
   "description": "Optional label, max 120 chars, no | character"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "3f2b8c1e-5d4a-4f7b-9a62-1c0e8d7f6a55",
  "hash": "0x1a19868d3b6b3f57f523b3202b9ae40155dc1491b3727c608f573acc615d9a0c",
  "label": "contract-v1",
  "signer": "0x02A5A59fdC30Ec50c091F7EE1486D08B49F56940",
  "message": "genexxis-notary:v1|stamp|0x1a19868d3b6b3f57f523b3202b9ae40155dc1491b3727c608f573acc615d9a0c|2026-10-24T20:55:00.123Z|contract-v1",
  "signature": "0x...65-byte signature",
  "timestamp": "2026-10-24T20:55:00.123Z",
  "verifyUrl": "https://notary.genexxis.com/verify"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/genexxis-notary-stamp-02b9ad4b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from notary.genexxis.com](https://www.zero.xyz/host/notary.genexxis.com/llms.txt)