The BitPay bitcoin payment gateway is the most versatile, easy-to-use bitcoin API available. The API is based on JSON and includes command line utilities that provide an easy-to-use client interface.
BitPay allows you to embed the invoice on your website, so the shopper never has to leave your site during the checkout process.
&view=iframeto the invoice URL and display this URL as the source in an iframe.
If your website has a dark background theme, append the code
&theme=dark to the invoice URL. Note that the iframe background color is transparent.