Skip to main content
POST
/
v1
/
verify
Verify Payment
curl --request POST \
  --url https://api.example.com/v1/verify
{
  "isValid": true,
  "message": "Payment authorization verified successfully",
  "details": {
    "verification_id": "vrf_b183c9692fac4481",
    "verified_amount": "20000",
    "verified_token": "0x036cbd53842c5426634e7929541ec2318f3dcf7e",
    "merchant_address": "0xa821f428ef8cc9f54a9915336a82220853059090",
    "payer_address": "0x78b6b8c55d5ea96be6ca8213e61b0fa53e862480",
    "verified_at": "2025-01-23T10:42:40Z"
  }
}

​
Endpoint

Verify that an EIP-3009 transferWithAuthorization signature is valid and meets expected criteria. Key principle: Customer authorizes payment to merchant address (not facilitator).
Verification is FREE. Only successful settlements incur the $0.01 fee.

​
Request Parameters

​
payment
object
required
Payment payload containing EIP-3009 authorization and signaturepayment.payload.authorization:
  • from: Customer address
  • to: MERCHANT address (where customer payment goes)
  • value: Payment amount in token’s smallest unit
  • validAfter: Unix timestamp (usually “0”)
  • validBefore: Unix timestamp (expiry)
  • nonce: Unique random bytes32
payment.payload.signature: EIP-712 signature from customer
​
requirements
object
required
Payment requirements from merchant’s 402 response
  • scheme: “exact”
  • price: “$0.02” (or atomic amount)
  • network: “eip155:84532” (CAIP-2 format)
  • payTo: Merchant address
  • token: USDC address (optional if using price)

​
Request Examples

curl -X POST https://facilitator.0xmeta.ai/v1/verify \
  -H "Content-Type: application/json" \
  -d '{
    "payment": {
      "x402Version": 2,
      "payload": {
        "authorization": {
          "from": "0x78b6b8c55d5ea96be6ca8213e61b0fa53e862480",
          "to": "0xA821f428Ef8cC9f54A9915336A82220853059090",
          "value": "20000",
          "validAfter": "0",
          "validBefore": "1735689600",
          "nonce": "0xee232e308a6647938a68aee1ae355b85a262e4e450b7fde55cd4e729e6444ce9"
        },
        "signature": "0x1e112204abec0856f56559b2d9a58d4e7bb5daec..."
      }
    },
    "requirements": {
      "scheme": "exact",
      "price": "$0.02",
      "network": "eip155:84532",
      "payTo": "0xA821f428Ef8cC9f54A9915336A82220853059090",
      "token": "0x036CbD53842c5426634e7929541eC2318f3dCF7e"
    }
  }'

​
Response Examples

{
  "isValid": true,
  "message": "Payment authorization verified successfully",
  "details": {
    "verification_id": "vrf_b183c9692fac4481",
    "verified_amount": "20000",
    "verified_token": "0x036cbd53842c5426634e7929541ec2318f3dcf7e",
    "merchant_address": "0xa821f428ef8cc9f54a9915336a82220853059090",
    "payer_address": "0x78b6b8c55d5ea96be6ca8213e61b0fa53e862480",
    "verified_at": "2025-01-23T10:42:40Z"
  }
}

​
Response Fields

​
isValid
boolean
required
Whether the payment authorization is valid
​
message
string
required
Human-readable verification result
​
details
object
details.verification_id: Use this for settlementdetails.verified_amount: Confirmed payment amountdetails.merchant_address: Merchant receiving paymentdetails.payer_address: Customer making paymentdetails.verified_at: ISO 8601 timestamp

​
Verification Process

​
What Gets Verified

1

Signature Validation

EIP-712 signature cryptographically verified using ecrecover
2

Recipient Validation

Critical: Authorization to address must match merchant address from requirements.payTo✅ authorization.to == requirements.payTo (merchant address)❌ authorization.to == treasury_address (wrong!)
3

Amount Validation

Authorization value matches expected amount exactly
4

Token Validation

Token address matches expected token (if specified)
5

Expiry Check

Current time is between validAfter and validBefore
6

Nonce Uniqueness

Nonce hasn’t been used in a previous settlement

​
Important Notes

Customer must authorize to MERCHANT address, not facilitator.The facilitator will reject authorizations to the treasury address. This maintains x402 trust-minimization.
Verification is FREE - unlimited verifications at no cost. Only successful settlements incur the $0.01 fee (collected from merchant’s approved balance).
Save the verification_id - you’ll need it for settlement! Store it with your order/transaction record.

​
Common Use Cases

{
  "payment": {
    "payload": {
      "authorization": {
        "to": "0xA821f428Ef8cC9f54A9915336A82220853059090",  // Merchant
        "value": "20000",  // $0.02
        ...
      }
    }
  },
  "requirements": {
    "payTo": "0xA821f428Ef8cC9f54A9915336A82220853059090",  // Same merchant
    "token": "0x036CbD53842c5426634e7929541eC2318f3dCF7e"  // USDC Sepolia
  }
}

{
  "requirements": {
    "price": "$0.02",
    "network": "eip155:8453",  // Base Mainnet
    "payTo": "0x...",  // Merchant address
    "token": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"  // USDC Mainnet
  }
}

​
Error Prevention

1

Use Merchant Address

Always set authorization.to = merchant address (not treasury)
2

Generate Unique Nonce

const nonce = "0x" + Array.from(crypto.getRandomValues(new Uint8Array(32)))
  .map(b => b.toString(16).padStart(2, "0"))
  .join("");
3

Set Long Validity

validBefore: String(Math.floor(Date.now() / 1000) + 86400)  // 24 hours
4

Match Amounts Exactly

Ensure authorization.value matches requirements.price or amount

​
Next Steps

Settle Payment

Execute settlement after verification

Error Handling

Handle verification failures

Architecture

Understand payment flow

Integration Guide

Complete setup guide
Verification complete! Use the verification_id to settle the payment.