There's several that you'll find integration projects for on github, personally I wrote my own lib to integrate Stripe and Paypal and much prefer stripe over paypal. it's a cleaner integration, faster flow for the user, lower fees, allows refunds for payments of any age whilst the card is valid and, for my clients, the money is paid out. Had lots of bad experience with Paypal withholding money for clients for over a year because they don't understand their business model and stopping refunds after 3 months even if the business allows them for longer