Send USD over Lightning
X-API-KEY header:Get the Wallet IDs and Check the Balances
Can run this query at any stage to confirm the change in the balances.
The "BTC" wallet balance is denominated in satoshis.
The "USD" wallet balance is in cents.
The body of the GraphQL request
query Me {
  me {
    defaultAccount {
      wallets {
        id
        walletCurrency
        balance
      }
    }
  }
}
Estimate the Payment Fee (Probe)
Estimate the cost of paying a lightning invoice. 
Payments to an other Blink user and to nodes with a direct channel are free.
The body of the GraphQL request
mutation lnUsdInvoiceFeeProbe($input: LnUsdInvoiceFeeProbeInput!) {
  lnUsdInvoiceFeeProbe(input: $input) {
    errors {
      message
    }
    amount
  }
}
curl command to probe invoice fee
Pay a Lightning Invoice
Pay a BOLT11 invoice from your USD balance.
The body of the GraphQL request
mutation LnInvoicePaymentSend($input: LnInvoicePaymentInput!) {
  lnInvoicePaymentSend(input: $input) {
    status
    errors {
      message
      path
      code
    }
  }
}
Send to a Lightning Address
Send to a Lightning Address from your USD balance.
The body of the GraphQL request
mutation LnAddressPaymentSend($input: LnAddressPaymentSendInput!) {
  lnAddressPaymentSend(input: $input) {
    status
    errors {
      code
      message
      path
    }
  }
}
Send to an LNURL
Send to a static LNURL payRequest from your USD balance.
The body of the GraphQL request
mutation LnurlPaymentSend($input: LnurlPaymentSendInput!) {
  lnurlPaymentSend(input: $input) {
    status
    errors {
      code
      message
      path
    }
  }
}
To test the GraphQL requests further use the GraphQL playground at api.blink.sv/graphql for mainnet or api.staging.blink.sv/graphql for staging.
Check out the Blink API Postman collection to find examples in multiple programming languages.