This is my simple implementation of Paypal Express Checkout for Codeigniter. It works as library and requires cURL. It is based from the codes I got from Paypal Lab Integration Wizard.

https://github.com/kidino/paypal_ec

More work to be done, but right now it only does the Sale Payment Action. No Order, Authorization and no recurring too. Not quite familiar with those.

Any feedbacks and comments are appreciated.