# Merchant side invoicing

{% hint style="info" %}
Implementation is **OPTIONAL**
{% endhint %}

### General Flow

1. Customer scans products to shopping cart.
2. Smarts will send shopping cart to merchant when customer is ready to pay for the purchase.
3. Merchant will response with generated receipt
4. Customer will pay for receipt.
5. Smarts will send receipt payment confirmation to merchant.

### Configuration

Visit your store configuration page in Smarts manager UI. Switch store side invoicing to **ON** position and implement required endpoints.

### Implementation

Implement following endpoints

[**Create receipt endpoint**](https://developer.smarts.ee/integration/custom-integration/merchant-side-invoicing/create-receipt)

[**Confirm receipt payment endpoint**](https://developer.smarts.ee/integration/custom-integration/merchant-side-invoicing/confirm-receipt-payment)