Skip to main content
A Billions integration connects four components:
  1. Your checkout, where the customer starts payment.
  2. Your backend, which creates and verifies invoices.
  3. The Billions hosted payment page.
  4. Your callback endpoint, which reacts to invoice updates.

​
Responsibilities

1

Prepare your account

Obtain an API key and decide which environment you will use.
2

Create invoices

Implement invoice creation on your backend with stable order references and idempotency keys.
3

Redirect customers

Send the customer to the hosted payment URL returned by the API.
4

Handle callbacks safely

Expose an HTTPS endpoint and retrieve the invoice from the API before changing order state.
5

Test failure paths

Cover retries, expired invoices, duplicate callbacks, and delayed payments.
6

Go live

Switch to production credentials and complete the launch checklist.

Prepare the integration

Gather credentials and define your order model.

Follow the payment flow

Implement invoice creation through final order confirmation.