react-credit-cards | Beautiful credit cards for your payment forms | Ecommerce library

Paypal allows both types of uses, from the client and from the server. I guess it's possible for the client to modify the request on their end to pay less. But, in the end, whatever your business is, you'll get an order and a payment. Just check if the payment is different than it should be and don't fulfil the order, make a refund.

If you want to save the trouble, then use the server option that makes the payment through your server.

In any case, like with any other payment method, I would recommend you take the time to implement it yourself following the great and well documented API provided by Paypal. They have a lot of examples and use cases, with code for the browser and the server.