Quick Start Guide

Get Started

Start accepting USDT payments in 5 minutes. This guide shows you how to integrate FromChain into your application.

Step 1: Get Your API Key

Contact our team to get your API credentials. You'll receive:

API Key

gw_live_your_key_here

Webhook Secret

whsec_your_secret_here

Step 2: Create Your First Invoice

Make a POST request to create a payment invoice:

create-invoice.js

const response = await fetch('https://api.fromchain.io/v1/invoices', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer gw_live_your_api_key_here',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    amountExpected: '100.00',
    externalId: 'order_12345',
    description: 'Payment for Order #12345',
    expiresInMinutes: 30
  })
});

const invoice = await response.json();
console.log('Deposit Address:', invoice.depositAddress);
console.log('Invoice ID:', invoice.id);

Response Example:

{
  "id": "inv_abc123",
  "depositAddress": "0x1234567890123456789012345678901234567890",
  "amountExpected": "100.00",
  "status": "PENDING",
  "expiresAt": "2025-12-18T12:30:00.000Z",
  "createdAt": "2025-12-18T12:00:00.000Z"
}

Step 3: Show Payment Instructions

Display the deposit address and amount to your customer:

display-payment.js

// Show this information to your customer
const paymentInfo = {
  address: invoice.depositAddress,
  amount: invoice.amountExpected,
  network: 'Binance Smart Chain (BSC)',
  token: 'USDT (BEP-20)'
};

// Display QR code, copy button, etc.
console.log('Send exactly', paymentInfo.amount, 'USDT to:');
console.log(paymentInfo.address);

Step 4: Handle Webhook Notifications

Set up a webhook endpoint to receive payment status updates:

webhook-handler.js

// Express.js example
app.post('/api/webhooks/fromchain', express.json(), (req, res) => {
  const event = req.body;
  
  // Verify webhook signature (see Security docs)
  const signature = req.headers['x-webhook-signature'];
  // ... verify signature ...
  
  switch (event.type) {
    case 'invoice.detected':
      console.log('Payment detected:', event.data.id);
      break;
      
    case 'invoice.confirmed':
      console.log('Payment confirmed:', event.data.id);
      // Update your database, fulfill order
      break;
      
    case 'invoice.paid_out':
      console.log('Funds sent to your wallet:', event.data.id);
      break;
      
    case 'invoice.failed':
      console.log('Payment failed:', event.data.id);
      break;
  }
  
  res.json({ received: true });
});

Step 5: Check Invoice Status

You can also poll the invoice status:

check-status.js

const response = await fetch(
  `https://api.fromchain.io/v1/invoices/${invoiceId}`,
  {
    headers: {
      'Authorization': 'Bearer gw_live_your_api_key_here'
    }
  }
);

const invoice = await response.json();

if (invoice.status === 'PAID_OUT') {
  console.log('Payment complete!');
  console.log('Received:', invoice.amountReceived, 'USDT');
  console.log('Your payout:', invoice.payoutAmount, 'USDT');
}