We are creating payment gateways extension. But we are facing API connect issue. Please provide guide line. So we can easily implement.
Can you be a little more specific?
Which API is having issues?
Actually I want to use Sagepay API but I have not idea, how to consume this API in payment gateway extension.
Did you know there is are well known SagePay modules? Maybe you won't need to develop the whole integration.
Take a look at the Marketplace: https://marketplace.magento.com/catalogsearch/result/?q=sagepay