# The Sealer Protocol – Onchain Attestation

> The Sealer Protocol – Onchain Attestation is a paid API for AI agents from thesealer.xyz, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-14).

Creates a cryptographically signed, on-chain attestation (statement, card, sleeve, or SID) for an AI agent or entity, proving wallet ownership and identity.

## Facts

- Endpoint: POST https://thesealer.xyz/api/attest
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/the-sealer-protocol-onchain-attestation-b5d860a4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_KlrXs6WtLcWMvI6SlFpLJ

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 the-sealer-protocol-onchain-attestation-b5d860a4 -d '<json body>'
```

Example prompt: Seal and certify my AI agent — wallet address 0xAbC123..., entity type AI_AGENT, using the 'card' format on Base, with the statement 'This agent is operated by Aria Labs and follows safe usage guidelines'; my agent name is 'Aria' and handle is 'aria.agent'.

## When to prefer this

Use this endpoint when an AI agent needs to create a verifiable, on-chain identity credential or accountability record — especially when the output must be cryptographically tied to a specific wallet address via EIP-712 signature. Prefer this over off-chain identity solutions when blockchain-native proof of agent identity, statement commitment, or certified SID is required on Base or Solana.

## Known failure modes

- Expired nonce (agentNonce must be within 5 minutes of current Unix time) — request rejected
- Invalid EIP-712 signature — authentication fails and attestation is not created
- Unsupported chain value — must be 'Base' or 'Solana'
- Invalid format enum — must be one of 'statement', 'card', 'sleeve', 'sid'
- Missing required fields (agentId, agentSig, agentNonce, format) — 400 Bad Request
- Image URL uses HTTP instead of HTTPS — rejected
- Payment failure — 0.1 USDC not received via x402 protocol

## How this service works

Onchain accountability for AI agents. Commit, prove, get certified.

## Output

Returns a certified attestation artifact (statement, card, sleeve, or SID) anchored on-chain (Base or Solana), proving that the agent at the specified wallet address committed to the given content at a specific timestamp, signed with an EIP-712 proof of wallet ownership.

## Request schema (JSON Schema)

```json
{
 "properties": {
  "input": {
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "format",
      "agentId",
      "agentSig",
      "agentNonce"
     ],
     "properties": {
      "format": {
       "type": "string"
      },
      "agentId": {
       "type": "string",
       "description": "EVM: your 0x wallet. Solana: your base58 public key."
      },
      "agentSig": {
       "type": "string",
       "description": "EIP-712 signature from your wallet proving ownership (EVM only)"
      },
      "agentNonce": {
       "type": "string",
       "description": "Unix timestamp (seconds) used when signing"
      },
      "statement": {
       "type": "string"
      },
      "theme": {
       "type": "string"
      },
      "imageUrl": {
       "type": "string"
      }
     }
    }
   }
  },
  "output": {
   "properties": {
    "example": {
     "status": "success",
     "txHash": "0xabc",
     "uid": "abc123",
     "permalink": "https://thesealer.xyz/c/abc123"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/the-sealer-protocol-onchain-attestation-b5d860a4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from thesealer.xyz](https://www.zero.xyz/host/thesealer.xyz/llms.txt)