presign-guard /v1/check

x402

presign-guard /v1/check is a paid API for AI agents from presign-guard.fizzl.eu, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-11).

Returns a green/orange/red safety verdict with reason codes for EVM transactions, token approvals, and typed-data signatures before they are signed

Price / call$0.01

Seller volume →—

Success—

StatusUnknown

How this service works

Is this transaction, approval or signature safe to sign? Check it before your AI agent or wallet signs it: pre-sign verdict (green/orange/red + reason codes) for EVM and Solana transactions, token approvals and Permit/Permit2/EIP-3009/Seaport signatures. Screens the spender or recipient wallet for OFAC sanctions and scam, phishing or theft reports, and flags unlimited allowances, plain-wallet spenders and risky tokens. Bulk: 100 checks for $0.80 via /v1/credits.

Output

A pre-sign verdict of green (safe), orange (caution), or red (dangerous) accompanied by structured reason codes such as OFAC_MATCH, SCAM_REPORTED, UNLIMITED_ALLOWANCE, PLAIN_WALLET_SPENDER, RISKY_TOKEN, NEW_DOMAIN, or similar flags explaining the risk level.

Example use cases

Unlimited allowance pre-sign check

“I'm about to approve an unlimited USDC allowance on Base (chain ID 8453) for spender 0x4752ba5dbc23f44d87826276bf6fd6b1c372ad24 — can you run a safety check and tell me if this is green, orange, or red before I sign?”

DeFi transaction screening before execution

“Check if this Ethereum transaction is safe to send: it's going to contract 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D on chain ID 1, with calldata 0x38ed1739000000000000000000000000000000000000000000000000002386f26fc10000 and 0 ETH value — give me the risk verdict.”

Seaport signature phishing check

“Before I sign this typed data from opensea.io, can you check if it's a legitimate Seaport order or a phishing attempt? Here's the eth_signTypedData_v4 payload on chain ID 1.”

Technical details

Endpoint

POSThttps://presign-guard.fizzl.eu/v1/check?utm_source=zero.xyz

When to prefer

Use this endpoint when an AI agent or automated wallet is about to sign any EVM transaction, token approval, or typed-data signature and needs a fast, structured safety verdict before execution. It is especially valuable for agentic DeFi workflows where the agent cannot rely on human review, for catching OFAC-sanctioned counterparties, unlimited allowances, or phishing-style Permit/Seaport signatures. Choose this over generic contract explorers when you need a machine-readable verdict (green/orange/red + reason codes) that can gate signing logic programmatically.

Side effects

Unsupported chain ID returns an error (only chains 1, 10, 56, 137, 8453, 42161 are supported)
Missing required fields for the chosen type (e.g. approval without spender) returns a 422 validation error
Malformed calldata or invalid address format causes a parsing error
Rate limiting or insufficient credits results in a 402 Payment Required response
Unrecognized typedData schema may produce an incomplete analysis

Input

Schema · Request body

Field	Type	Description
to	string	transaction: target contract
tx	object	xrpl: the unsigned transaction JSON
data	string	transaction: 0x-prefixed calldata
from	string	optional: your wallet; an EVM transaction is then simulated
lang	string	explain only: en or nl
type	string	What is about to be signed
x402	object	optional, EIP-3009 payments: the x402 accepts entry being paid
token	string	approval: token contract
value	string	transaction: native value in wei
amount	string	approval: amount in base units (0 = revoke)
intent	string	optional: what the agent means to do, in one sentence
method	string	message: personal_sign (default) or eth_sign
origin	string	optional: the site asking (URL or hostname)
chainId	integer	EVM chain; required for approval, transaction and signature
mandate	object	optional, EIP-3009 payments: the spending mandate paid under
message	string	message: the text or 0x-hex to be signed
network	string	xrpl: xrpl:0 (default) or xrpl:1
spender	string	approval: who gets the allowance
typedData	—	signature: the eth_signTypedData_v4 payload
transaction	string	solana: the base64 wire transaction; algorand: one base64 msgpack transaction
transactions	array	algorand: an atomic group, each base64 msgpack

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