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POST
/
x402
/
pay
Pay External Service
curl --request POST \
  --url https://api.example.com/x402/pay \
  --header 'Content-Type: application/json' \
  --data '
{
  "url": "<string>",
  "method": "<string>",
  "headers": {},
  "body": "<string>"
}
'

​
Overview

The x402 endpoint lets your agent pay any external service that supports the x402 protocol (HTTP 402 Payment Required). MIDAS acts as a proxy:
  1. Makes the HTTP request on your behalf
  2. If the service returns 402 Payment Required, MIDAS parses the payment requirements
  3. Signs an EIP-3009 transferWithAuthorization using your agent’s Base wallet
  4. Retries the request with the PAYMENT-SIGNATURE header
  5. Returns the service response to you
Protocol fees (1.5%) apply. Transaction limits based on your reputation tier apply.

​
Request

​
url
string
required
The target URL to call. Must be a valid HTTPS URL.
​
method
string
default:"GET"
HTTP method: GET, POST, PUT, PATCH, or DELETE.
​
headers
object
Optional headers to forward to the target service.
​
body
string
Request body for POST/PUT/PATCH requests. Max 50KB.

​
Example

curl -X POST https://api.midasprotocol.org/x402/pay \
  -H "Authorization: Bearer pp_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://api.example.com/premium-data",
    "method": "GET"
  }'

​
Response (no payment needed)

If the target service does not require payment, the response is proxied directly: 
{
  "success": true,
  "statusCode": 200,
  "headers": { "content-type": "application/json" },
  "body": "{\"data\": \"...\"}"
}

​
Response (payment settled)

If the service returned 402 and MIDAS paid successfully: 
{
  "success": true,
  "statusCode": 200,
  "headers": { "content-type": "application/json" },
  "body": "{\"data\": \"premium content\"}",
  "payment": {
    "amount": "0.01",
    "asset": "USDC",
    "network": "eip155:8453",
    "payTo": "0x...",
    "protocolFee": "0.00015"
  }
}

​
Response (payment failed)

{
  "success": false,
  "statusCode": 402,
  "headers": {},
  "body": "[...]",
  "error": "No compatible payment requirement found. MIDAS supports exact scheme on Base (eip155:8453) with USDC."
}

​
Supported Payment Schemes

SchemeNetworkAssetStatus
exact (EIP-3009)Base (eip155:8453)USDCSupported

​
Prerequisites

  • Your agent must have a blockchain wallet (automatically created at registration)
  • Sufficient USDC balance in your internal wallet
  • Transaction must be within your reputation tier limit

​
How It Works (Technical)

  1. MIDAS makes the initial HTTP request
  2. On 402 response, parses PAYMENT-REQUIRED header or response body
  3. Selects a compatible payment requirement (exact scheme, Base network, USDC)
  4. Decrypts the agent’s private key and signs an EIP-3009 TransferWithAuthorization
  5. Retries with both X-PAYMENT and PAYMENT-SIGNATURE headers
  6. On success, debits the agent’s internal USDC balance + 1.5% protocol fee