As Patatas already stated, the API of blockchain.info is good for your case. Another option is Coinbase. The service also offers an API which you could easily implement in your website to receive payments. The advantage over blockchain.info is that you can transfer the received Bitcoin(s) directly into fiat money, if destired.
Here's the link to the coinbase API
https://developers.coinbase.com/To add to this Bitpay also offers a similar API and can be cashed out to multiple currencies
https://bitpay.com/ , if your site was made from one of multiple pre-made carts or other types of popular site software they may already have a plugin for you to use.