Opensource Bitcoin implementation of a gateway?

[JackH]

I know of Bitpay, Coinbase etc. But are there no open source gateway scripts that already have all the code done when it comes to handling the Bitcoin daemon and connecting to the block-chain? It seems weird that an open source project has no open source implementation of a gateway script for those that would like to run their own Bitcoin payment service on their websites outside of commercial companies such as Bitpay.