Knowhow

https://techtolia.com/PayPal/

PayPal is one of the most popular Online Payment Processing System available in more than 200 countries/regions and support 25 currencies.

Once you sign up and confirm your account, PayPal provides you with a set of API keys. Basically you get a “Client Id” key and a “Client Secret” key. https://developer.paypal.com/home/

Logging into the Developer Dashboard to get credentials and create sandbox accounts requires a developer, personal, or business account. Each account provides different levels of access to PayPal functionality. Developer Account: access sandbox, Personal Account: access sandbox+send and receive money, Business Account: access sandbox+send and receive money+go live

If you are looking a solution to integrate PayPal’s checkout to your website that is builded with .Net & C#, look at that demo https://techtolia.com/PayPal/

With integrating and customizing the application, receive payments from PayPal, PayPal Credit, credit or debit cards, Bancontact, BLIK, eps, giropay, iDEAL, MyBank, Przelewy24, SEPA-Lastschrift, Sofort, Venmo via PayPal.

PayPal auto detects the country from the buyer’s IP geolocation and generates payment options with buttons.
Payment Methods powered by PayPal (over 200 countries and regions):

• PayPal

• Credit or debit cards

• PayPal Credit: US

• Bancontact: Belgium

• BLIK: Poland

• eps: Austria

• giropay: Germany

• iDEAL: Netherlands

• MyBank: Italy

• Przelewy24: Poland

• SEPA-Lastschrift: Germany

• SOFORT: Austria, Belgium, Germany, Italy, Netherlands, Spain

• Venmo: US (and with US merchants) (on a mobile browser)

Elements are completely customizable. You can style Elements to match the look and feel of your site, providing a seamless checkout experience for your customers.

Target Framework: .NET Framework 4.7.2 - Language: c#

Purchase on CodeCanyon
https://codecanyon.net/item/paypal-checkout-in-aspnet-web-forms-c-using-orders-v2-rest-api-serverside-integration/27534910
PayPal Checkout in ASP.NET Web Forms & C#, Using Orders v2 REST API, Server-side Integration