Buyer identity

Identify who paid with customer_email and external_reference — or stay anonymous with an explicit warning.

Ulasend does not require the end buyer to log into Ulasend. Identity comes from what you pass when creating the invoice.

Recommended: pass both

{
  "usd_amount": "25.00",
  "customer_email": "buyer@example.com",
  "external_reference": "user_42_order_99"
}

Both fields are returned on the invoice object and on every webhook. Match them to your database and fulfill.

Anonymous invoices are allowed

If you omit both fields, create still succeeds — but the response includes a warningsarray telling you that you won't be able to match the payment to a buyer unless you store this invoice's id against the buyer yourself and handle invoice.paid.

Who controls this?

Actor	Role
Your app (merchant)	Decides whether to send email / reference on create
End buyer	Only pays on `/pay/…` — they do not set these fields