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presign-guard /v1/check/explain
x402
presign-guard /v1/check/explain is a paid API for AI agents from presign-guard.onrender.com, paid per call via x402, $0.03/call, status unknown (last checked 2026-10-11).
Returns a pre-sign risk verdict (green/orange/red) plus a plain-language explanation in English or Dutch for a transaction, token approval, or signature
Price / call$0.03
Success—
StatusUnknown
How this service works
Pre-sign risk verdict plus a plain-language explanation in Dutch or English
Output
A JSON response containing a risk verdict (green, orange, or red), and a plain-language explanation in English or Dutch describing what the transaction/approval/signature does, why it is or isn't risky, and any specific red flags detected such as unlimited approvals, new domains, or known exploit patterns.
Example use cases
Explain risky DeFi approval before signing
“I'm about to approve a DeFi protocol to spend my USDC on Ethereum mainnet — the spender is 0x1111111254EEB25477B68fb85Ed929f73A960582, the token is 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48, and the amount is max (unlimited). Can you give me a plain-English explanation of what this approval does and whether it's safe to sign?”
Check Permit2 typed data signature
“My wallet is asking me to sign a Permit2 typed data payload from the site uniswap.org on Base (chain 8453). Here's the typedData object — can you explain what I'd be authorizing and give me a green, orange, or red verdict on whether I should sign it?”
Assess suspicious transaction in Dutch
“Ik krijg een transactieverzoek van een site die ik niet ken — de contractopdrachtgever is 0xDeadBeef... met calldata 0xa9059cbb... op chain 137. Kan je in het Nederlands uitleggen wat deze transactie doet en of ik het veilig kan ondertekenen?”
Technical details
Endpoint
POSThttps://presign-guard.onrender.com/v1/check/explain?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need not just a pass/fail verdict but a human-readable explanation of why a transaction or approval is risky — especially useful when the agent must relay the reasoning to a non-technical user. It is ideal when you need bilingual support (Dutch or English) or when the user wants to understand a complex EIP-712 typed data payload such as Permit, Permit2, or Seaport orders before signing. Prefer the sibling /check endpoint if you only need the verdict and reason code without a verbose explanation.
Side effects
- Unsupported chainId (not in [1,10,56,137,8453,42161]) returns validation error
- Missing required fields for the given type (e.g. no 'to' or 'data' for a transaction) returns error
- Malformed calldata or invalid contract address returns parsing error
- Unrecognized typed data schema may result in lower-confidence verdict
- Payment failure (x402) blocks the request if USDC payment is not attached
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| to | string | transaction: target contract |
| data | string | transaction: 0x-prefixed calldata |
| lang | string | explain only: language of the explanation (default en) |
| type | string | What the agent is about to sign |
| token | string | approval: token contract |
| value | string | transaction: native value in wei |
| amount | string | approval: amount in base units (0 = revoke) |
| origin | string | optional: the site asking for the signature or transaction (URL or hostname); a domain under 30 days old is orange |
| chainId | integer | |
| spender | string | approval: who gets the allowance |
| typedData | — | signature: the eth_signTypedData_v4 payload (Permit, Permit2, EIP-3009 x402 payment, Seaport) |
Tags
x402
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