ctCryptoPayLib is Catalina Technology's FREE .net library allowing quick integration of merchant funtions for bitcoin payment processors: bitpay and coinbase.
ctCryptoPayLib is built on the .NET framework and easy to integrate with your website or custom client application. This is the same library Catalina Technology uses for our ctCryptoPay SOAP web service.
Bitpay api features:

  • createInvoice - Request invoice with passed values.
  • getInvoice - Get an existing invoice and status
  • getAllCurrencyRates - Gets all current rates
  • getCurrencyRate - Gets a single currency exchange rate

Coinbase api features:
  • getCurrencyRate - Gets curent rate in given currency
  • createButton - Creates a button with the passed params
  • createOrder - Creates an order associated with a button
  • getOrder - Gets an order by ID
  • requestMoney - Send a Request for money

See: ctCryptoPayLib Programmers Reference