> ## Documentation Index
> Fetch the complete documentation index at: https://docs.billions.works/llms.txt
> Use this file to discover all available pages before exploring further.

# Create an invoice

> Create a hosted payment invoice with an SDK.

This example creates a `100 USDT` invoice for `ORDER-1001`.

<CodeGroup>
  ```ts TypeScript theme={null}
  import { BillionsApi } from '@billions-works/sdk-ts';

  const api = new BillionsApi({
    apiKey: process.env.BILLIONS_API_KEY!,
  });

  const invoice = await api.createInvoice({
    currency: 'USDT',
    amount: 100,
    order_no: 'ORDER-1001',
    idempotencyKey: 'ORDER-1001-attempt-1',
    callbackUrl: 'https://example.com/webhooks/billions',
  });

  console.log(invoice.id);
  console.log(invoice.invoice_url);
  ```

  ```php PHP theme={null}
  <?php

  require 'vendor/autoload.php';

  use Billions\BillionsApi;

  $api = new BillionsApi($_ENV['BILLIONS_API_KEY']);

  $invoice = $api->createInvoice([
      'currency' => 'USDT',
      'amount' => 100,
      'order_no' => 'ORDER-1001',
      'idempotencyKey' => 'ORDER-1001-attempt-1',
      'callbackUrl' => 'https://example.com/webhooks/billions',
  ]);

  echo $invoice['id'] . PHP_EOL;
  echo $invoice['invoice_url'] . PHP_EOL;
  ```

  ```bash cURL theme={null}
  curl --request POST \
    --url https://api.billions.works/public/v1/invoices/create \
    --header "Content-Type: application/json" \
    --header "x-api-key: $BILLIONS_API_KEY" \
    --data '{
      "currency": "USDT",
      "amount": 100,
      "order_no": "ORDER-1001",
      "idempotencyKey": "ORDER-1001-attempt-1",
      "callbackUrl": "https://example.com/webhooks/billions"
    }'
  ```
</CodeGroup>

## What to store

Store the returned invoice ID with your order before redirecting the customer.
Also retain the order number, idempotency key, status, and expiration time.

## What to do next

Redirect the customer to `invoice_url`, then implement
[callback handling](/examples/handle-a-callback).