# SignalHarness EIP-712 Typed Data Hash

> SignalHarness EIP-712 Typed Data Hash is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-16).

Computes the EIP-712 typed data hash for a given structured data input, returning the canonical hash used for Ethereum typed structured data signing.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/typed_data_hash_eip712/invoke
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-eip-712-typed-data-hash-9d439701
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_R2NFhl3mPbQ5lh2zaTpbO

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 signalharness-eip-712-typed-data-hash-9d439701 -d '<json body>'
```

Example prompt: Can you compute the EIP-712 typed data hash for this structured data payload I need to sign on Ethereum? Here's the typed data JSON: {"domain":{"name":"MyApp","version":"1","chainId":1},"types":{"Mail":[{"name":"from","type":"address"},{"name":"to","type":"address"},{"name":"contents","type":"string"}]},"message":{"from":"0xabc...","to":"0xdef...","contents":"Hello!"}}

## When to prefer this

Use this endpoint when you need a reliable, pay-per-use EIP-712 typed data hash computation without running your own Ethereum tooling or library. Particularly useful for AI agents operating in blockchain workflows that need to compute or verify EIP-712 hashes on demand without setting up ethers.js or viem locally. Prefer this over generic hashing APIs when you specifically need EIP-712 structured data encoding semantics.

## Known failure modes

- Invalid or malformed typed data JSON returns an error
- Typed data exceeding 65536 characters is rejected
- Missing required EIP-712 fields (domain, types, message) causes failure
- Input shorter than 2 characters is rejected by schema validation
- Network or payment failure returns a failed status in the receipt

## How this service works

Explore 330 pay-per-call x402 API services and 27 agent-native digital products, with Base USDC pricing, secure Polar checkout, and free discovery.

## Output

Returns a JSON object containing the computed EIP-712 typed data hash (as a hex string), any warnings about the input data, the evidence scope indicating the data was caller-supplied, and the service ID. Also includes a full receipt with payment details, network, execution timing, request/execution IDs, and a SHA-256 of the result for auditability.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "typed_data_hash_request": {
   "type": "string",
   "maxLength": 65536,
   "minLength": 2
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "Hashing does not sign, submit, or validate application intent."
   ],
   "service_id": "typed_data_hash_eip712",
   "evidence_scope": "caller_supplied_data",
   "typed_data_hash": "{\"hash\":\"0x8db8c5ec3114da2288a018bc3f8bae3e5e0ef77c3848832fe9adbea12c047e1b\",\"primary_type\":\"Note\"}"
  },
  "status": "succeeded",
  "receipt": {
   "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
   "usage": [],
   "status": "succeeded",
   "network": "eip155:8453",
   "artifacts": [],
   "endedAtMs": 0,
   "latencyMs": 0,
   "paymentId": "example-payment",
   "receiptId": "example-receipt",
   "requestId": "example-request",
   "serviceId": "typed_data_hash_eip712",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "76ea22f78bfba3dcbd2a4b5f3273c9ff5a2e045f87018ad4f2fe487745d9106a",
   "serviceVersion": "1.0.0",
   "settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
  },
  "artifacts": [],
  "requestId": "example-request",
  "executionId": "example-execution"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signalharness-eip-712-typed-data-hash-9d439701/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from signalharness.ai](https://www.zero.xyz/host/signalharness.ai/llms.txt)