There are two ways that you could integrate with DOKU. You can either use our Checkout API or Direct API. Checkout API is an easier integration method where you would have DOKU's checkout and payment page integrated with your website. Direct API is a more customizable integration method as you can have the checkout and payment page shown on your website.
You may check the demo of DOKU Checkout API and Direct API here.
DOKU also supports integration via e-commerce or plugins such as Magento, WordPress (WooCommerce), Shopify, PrestaShop, OpenCart, and many more.
Visit DOKU API Documentation to learn more.