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SignalHarness EIP-712 Typed Data Hash
x402
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 2026-09-13).
Computes the EIP-712 typed data hash for a given structured data input, returning the canonical hash used for Ethereum typed structured data signing.
Price / call$0.01
Success—
StatusUnknown
How this service works
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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.
Example use cases
Sign typed permit for DeFi transaction
“I need to sign a Unipermit typed data message for a token approval — can you compute the EIP-712 hash for this payload before I send it to my wallet for signing? Here's the typed data: {"domain":{"name":"Uniswap","chainId":1},"types":{"Permit":[{"name":"owner","type":"address"},{"name":"value","type":"uint256"}]},"message":{"owner":"0x123...","value":"1000000"}}”
Validate EIP-712 hash before contract submission
“Before I submit this typed data to my smart contract, can you compute the EIP-712 hash so I can double-check it matches what my contract expects? My typed data is: {"domain":{"name":"VaultProtocol","version":"2","chainId":8453},"types":{"Withdraw":[{"name":"amount","type":"uint256"},{"name":"nonce","type":"uint256"}]},"message":{"amount":"500000000","nonce":"3"}}”
Debug signature mismatch in dApp
“My dApp is producing a signature mismatch — can you compute the EIP-712 typed data hash for this payload so I can see if the hash my frontend generates matches? Here's the typed data object: {"domain":{"name":"MyNFT","version":"1","chainId":137},"types":{"Mint":[{"name":"to","type":"address"},{"name":"tokenId","type":"uint256"}]},"message":{"to":"0xabc...","tokenId":"42"}}”
Technical details
Endpoint
POSThttps://signalharness.ai/api/agent/services/typed_data_hash_eip712/invokeWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| typed_data_hash_request | string |
Output
Schema · Response
{
"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"
}
}Tags
x402
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