presign-guard
Is this transaction, approval or signature safe to sign, explained for a person? The same pre-sign verdict as /v1/check (green/orange/red + reason codes) plus a short plain-language explanation in English or Dutch, for an agent to show its user before asking for approval. Bulk: 100 checks for $0.80 via /v1/credits.
Offering
- Provider
- presign-guard.fizzl.eu
- Method
- POST
- Offering type
- Api Endpoint
- Transport type
- http
- Category
- Security
- Delivery
- Not provided
- Pricing model
- Not provided
- x402 version
- 2
Endpoint context
- URL
https://presign-guard.fizzl.eu/v1/check/explain- MIME type
- application/json
- First seen
- 2026-10-16T01:50:38.788Z
- Last seen
- Tags
- wallet-security, pre-sign, approvals, sanctions, Agents
Payment pricing
x402 payment terms are the authoritative price for calling this endpoint.
- Payment option 1
- 0.03 USDC
Atomic price: 30000 · Network: eip155:8453 · Asset: USDC · Scheme: exact - Payment option 2
- 0.03 USDC
Atomic price: 30000 · Network: solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp · Asset: USDC · Scheme: exact - Payment option 3
- 30000 atomic units
Atomic price: 30000 · Network: algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73k · Asset: 31566704 · Scheme: exact - Payment option 4
- 300000 atomic units
Atomic price: 300000 · Network: stellar:pubnet · Asset: CCW67TSZV3SSS2HXMBQ5JFGCKJNXKZM7UQUWUZPUTHXSTZLEO7SJMI75 · Scheme: exact - Payment option 5
- 30000 atomic units
Atomic price: 30000 · Network: eip155:196 · Asset: 0x779ded0c9e1022225f8e0630b35a9b54be713736 · Scheme: exact - Payment option 6
- 0.03 USDC
Atomic price: 30000 · Network: eip155:143 · Asset: USDC · Scheme: exact
Raw x402 terms
[
{
"scheme": "exact",
"network": "eip155:8453",
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"amount": "30000",
"payTo": "0x6B0F4651eD42893ab58139938175E4a69f175F25"
},
{
"scheme": "exact",
"network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
"asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
"amount": "30000",
"payTo": "ATWJ82T8nRdQwZnaysB68N5EpaSvLRsQP4h6eWmaJBH9"
},
{
"scheme": "exact",
"network": "algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73k",
"asset": "31566704",
"amount": "30000",
"payTo": "LOYVFSQ6ZTS2YWUW4GQ5L6VPP2TPIOXWYDACK53CPOHQQHLDMEMKJDXAX4"
},
{
"scheme": "exact",
"network": "stellar:pubnet",
"asset": "CCW67TSZV3SSS2HXMBQ5JFGCKJNXKZM7UQUWUZPUTHXSTZLEO7SJMI75",
"amount": "300000",
"payTo": "GCH2J5UAY24YNKA65MPAATVKWRCZZRZNF3JZKYYS5MIBZPG6U7WJ6CDQ"
},
{
"scheme": "exact",
"network": "eip155:196",
"asset": "0x779ded0c9e1022225f8e0630b35a9b54be713736",
"amount": "30000",
"payTo": "0x6B0F4651eD42893ab58139938175E4a69f175F25"
},
{
"scheme": "exact",
"network": "eip155:143",
"asset": "0x754704Bc059F8C67012fEd69BC8A327a5aafb603",
"amount": "30000",
"payTo": "0x6B0F4651eD42893ab58139938175E4a69f175F25"
}
]Observed health
- Status
- Healthy
- Latest latency
- 138 ms
- Average latency
- 1626 ms
- HTTP status
- 200
- Last checked
- Reachability
- 88.9% over 9 checks
Latency is measured to the first response headers. A reachable result does not verify response accuracy or merchant identity.
Input schema
{
"type": "object",
"properties": {
"type": {
"type": "string",
"const": "http"
},
"method": {
"type": "string",
"enum": [
"POST"
]
},
"bodyType": {
"type": "string",
"enum": [
"json",
"form-data",
"text"
]
},
"body": {
"type": "object",
"properties": {
"type": {
"type": "string",
"enum": [
"approval",
"transaction",
"signature",
"authorization",
"message",
"solana",
"xrpl",
"algorand",
"stellar",
"near"
],
"description": "What is about to be signed"
},
"address": {
"type": "string",
"description": "authorization: the contract the EIP-7702 authorization delegates the wallet to ("
},
"authorizationChainId": {
"type": "integer",
"description": "authorization, optional: the chain id inside the authorization, chainId (default"
},
"nonce": {
"type": "string",
"description": "authorization, optional: the authorization nonce"
},
"transaction": {
"type": "string",
"maxLength": 12000,
"description": "solana: base64 wire tx; algorand: base64 msgpack tx; stellar: base64 XDR envelope"
},
"transactions": {
"type": "array",
"maxItems": 16,
"items": {},
"description": "algorand: an atomic group, each base64 msgpack"
},
"method": {
"type": "string",
"enum": [
"personal_sign",
"eth_sign"
],
"description": "message: personal_sign (default) or eth_sign"
},
"message": {
"type": "string",
"maxLength": 16384,
"description": "message: the text or 0x-hex to be signed"
},
"chainId": {
"type": "integer",
"enum": [
1,
10,
56,
137,
143,
196,
8453,
42161,
4663,
43114
],
"description": "EVM chain; required for approval, transaction and signature"
},
"network": {
"type": "string",
"enum": [
"xrpl:0",
"xrpl:1",
"stellar:pubnet",
"stellar:testnet"
],
"description": "xrpl: xrpl:0 (default) or xrpl:1; stellar: stellar:pubnet (default) or stellar:testnet"
},
"nep413": {
"type": "object",
"description": "near: a NEAR Intents message about to be signed ({ message, recipient, nonce }, "
},
"tx": {
"type": "object",
"description": "xrpl: the unsigned transaction JSON"
},
"token": {
"type": "string",
"description": "approval: token contract"
},
"spender": {
"type": "string",
"description": "approval: who gets the allowance"
},
"amount": {
"type": "string",
"description": "approval: amount in base units (0 = revoke)"
},
"to": {
"type": "string",
"description": "transaction: target contract"
},
"data": {
"type": "string",
"description": "transaction: 0x-prefixed calldata"
},
"value": {
"type": "string",
"description": "transaction: native value in wei"
},
"from": {
"type": "string",
"description": "optional: your wallet; an EVM transaction is then simulated"
},
"typedData": {
"type": [
"object",
"string"
],
"description": "signature: the eth_signTypedData_v4 payload"
},
"origin": {
"type": "string",
"description": "optional: the site asking (URL or hostname)"
},
"intent": {
"type": "string",
"maxLength": 500,
"description": "optional: what the agent means to do, in one sentence"
},
"x402": {
"type": "object",
"description": "optional, EIP-3009 payments: the x402 accepts entry being paid"
},
"mandate": {
"type": "object",
"description": "optional, EIP-3009 payments: the spending mandate paid under"
},
"lang": {
"type": "string",
"enum": [
"en",
"nl"
],
"description": "explain only: en or nl"
}
},
"required": [
"type"
]
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"additionalProperties": false
}Output schema
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"properties": {
"amount": {
"description": "approval: amount in base units (0 = revoke)",
"type": "string"
},
"chainId": {
"description": "EVM chain; required for approval, transaction and signature",
"enum": [
1,
10,
56,
137,
8453,
42161
],
"type": "integer"
},
"data": {
"description": "transaction: 0x-prefixed calldata",
"type": "string"
},
"lang": {
"description": "explain only: language of the explanation (default en)",
"enum": [
"en",
"nl"
],
"type": "string"
},
"mandate": {
"description": "optional, EIP-3009 payments only: the spending mandate the agent pays under (x402 authority extension, x402-mandate/1): { mandate, alg: \"Ed25519\", sig, paymentId }. Outside it (over perPayment or cap, other recipient, payer or token, expired, bad signature, nonce not the mandate binding) is red",
"type": "object"
},
"network": {
"description": "xrpl: the ledger (default xrpl:0, mainnet)",
"enum": [
"xrpl:0",
"xrpl:1"
],
"type": "string"
},
"origin": {
"description": "optional: the site asking for the signature or transaction (URL or hostname); a domain under 30 days old is orange",
"type": "string"
},
"spender": {
"description": "approval: who gets the allowance",
"type": "string"
},
"to": {
"description": "transaction: target contract",
"type": "string"
},
"token": {
"description": "approval: token contract",
"type": "string"
},
"tx": {
"description": "xrpl: the unsigned transaction JSON (TransactionType, Account, ...). Red: SetRegularKey/SignerListSet to another key, disabling the master key, AccountDelete, fake RLUSD; orange: partial payments, destinations that refuse or need a tag, issuers that can claw back or freeze, escrows and NFT giveaways",
"type": "object"
},
"type": {
"description": "What the agent is about to sign (xrpl: an XRP Ledger transaction)",
"enum": [
"approval",
"transaction",
"signature",
"xrpl"
],
"type": "string"
},
"typedData": {
"description": "signature: the eth_signTypedData_v4 payload (Permit, Permit2, EIP-3009 x402 payment, Seaport)",
"type": [
"object",
"string"
]
},
"value": {
"description": "transaction: native value in wei",
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"properties": {
"explanation": {
"properties": {
"lang": {
"type": "string"
},
"text": {
"type": "string"
}
},
"type": "object"
},
"reasons": {
"items": {
"properties": {
"code": {
"type": "string"
},
"details": {},
"severity": {
"enum": [
"red",
"orange",
"info"
],
"type": "string"
},
"subject": {
"type": "string"
}
},
"required": [
"code",
"severity"
],
"type": "object"
},
"type": "array"
},
"receipt": {
"description": "Signature over this whole answer (without receipt.signature), so the verdict can be verified later: EIP-191 personal_sign over canonical JSON (sorted keys, compact, ASCII-escaped). Signer addresses: /.well-known/presign-guard-signer.json; free check: POST /v1/verify.",
"properties": {
"algorithm": {
"enum": [
"eip191-canonical-json-v1"
],
"type": "string"
},
"cert": {
"description": "The payout wallet's certificate for this signing key: personal_sign by authority over 'fizzl receipt signer\\nservice: <service>\\nsigner: <signer>\\nvalid_from: <date>'. Pin the payout wallet and a rotated key still verifies.",
"properties": {
"authority": {
"type": "string"
},
"service": {
"type": "string"
},
"signature": {
"type": "string"
},
"signer": {
"type": "string"
},
"valid_from": {
"type": "string"
}
},
"type": "object"
},
"input_sha256": {
"description": "sha256 of canonical JSON {route, input}: your body (POST) or query parameters (GET)",
"type": "string"
},
"payment": {
"description": "The payment behind this answer, from your x402 payment payload. EVM: payer + EIP-3009 nonce; find the settlement as AuthorizationUsed(payer, nonce) on the asset contract. Solana: payer + sha256 of the signed transaction you sent.",
"properties": {
"amount": {
"type": "string"
},
"asset": {
"type": "string"
},
"network": {
"type": "string"
},
"nonce": {
"type": "string"
},
"pay_to": {
"type": "string"
},
"payer": {
"type": "string"
},
"proof": {
"enum": [
"eip3009",
"svm-transaction"
],
"type": "string"
},
"transaction_sha256": {
"type": "string"
}
},
"type": "object"
},
"request_id": {
"type": "string"
},
"route": {
"type": "string"
},
"signature": {
"type": "string"
},
"signed_at": {
"type": "string"
},
"signer": {
"type": "string"
}
},
"required": [
"request_id",
"route",
"input_sha256",
"signed_at",
"signer",
"algorithm",
"signature"
],
"type": "object"
},
"subject": {
"type": "object"
},
"verdict": {
"enum": [
"green",
"orange",
"red"
],
"type": "string"
}
},
"required": [
"verdict",
"reasons"
],
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}