Quickstart

1. Get an API key

In the Ulasend dashboard, create a test key (pk_test_…). Store it as an environment variable on your server — never in frontend code:

export ULASEND_API_KEY="pk_test_xxxxxxxx"

2. Create an invoice for this order

Call Ulasend from your backend when the buyer is ready to pay. Pass this cart's dollar total as usd_amount:

curl -X POST https://ulasend.com/api/v1/invoices \
  -H "Authorization: Bearer $ULASEND_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: order-12345" \
  -d '{
    "usd_amount": "49.99",
    "asset": "USDC_BASE",
    "customer_email": "buyer@example.com",
    "external_reference": "order-12345",
    "allow_asset_selection": true
  }'

3. Send the buyer to checkout

Redirect them to checkout_url in the response. They pay with a wallet QR, or (when enabled) buy crypto with a card. Card purchases default to USDC unless they pick another coin first. Choose which coins you accept under Settings → Accepted coins.

4. Fulfill on the webhook

Listen for invoice.paid. Match external_reference or customer_email to your order, then fulfill in your system. See Webhooks.