Web3 USDT Component | Blockonomics API

Embed a ready-made Web3 component that lets customers pay USDT from MetaMask or any browser wallet.

Overview

The Web3 USDT Component handles wallet connection, network validation, and ERC-20 transfer signing in a single embeddable element. Drop it on your USDT checkout page and it takes care of the browser wallet interaction.

Embed the Component

html

<!-- Include the component script -->
<script src="https://blockonomics.co/js/web3-payment.js"></script>

<!-- Place the component in your HTML -->
<web3-payment
  id="web3_payment"
  order_amount="10"
  receive_address="YOUR_USDT_RECEIVE_ADDRESS"
  testnet="0"
></web3-payment>

Attributes

Attribute	Description
`order_amount`	Amount of USDT the customer must pay
`receive_address`	Your USDT (ERC-20) receiving address
`testnet`	`0` for Ethereum mainnet, `1` for Sepolia testnet

Screenshot of web3 USDT component on checkout page

Screenshot of web3 USDT component on checkout page

Handle Payment Submission

When the customer approves the transaction in their wallet, the component fires onTxnSubmitted with the txhash and crypto:

javascript

const web3Payment = document.getElementById('web3_payment');

web3Payment.onTxnSubmitted = function(result) {
  const { crypto, txhash } = result;

  // Send to your backend for monitoring
  fetch('/api/payments/confirm', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ txhash, crypto })
  });
};

Register for Monitoring

Your backend must submit the txhash to Blockonomics so it can track confirmation. See Monitor USDT Transaction for the API details.

Handle Callbacks

Once registered, Blockonomics sends a callback to your server when the transaction confirms on-chain. Mark the order as paid at that point — not when onTxnSubmitted fires.