1. As of March 2018, the following payment processors are compatible with Funnel Builder:
2. If you want to use one-click upsells with Paypal, then you will need to have reference transactions enabled. To have them enabled you will have to email or speak to Paypal to enable it on your account. You may need to be persistent and fill in extra forms, but once this is done, it is enabled for ever more.
3. The instructions of how to integrate Paypal/Stripe/Bluesnap can be found in the help section (where you are reading this).
4. If you want to use Recharge, they currently natively allow Braintree (which includes Paypal) and Stripe. There are other hacks out there to use other processors with Recharge such as Authorize.net, but you will need to speak with Recharge directly about that.
5. Therefore, if you want to use Recharge within Funnel Buildr, you will have to use Stripe.
6. The payment processor that you use on your main Shopify store does not have a connection to Funnel Buildr. Funnel Buildr uses the settings which you put in Funnel Buildr. Therefore, if you are using Payment Processor A on the main Shopify store and this does not work within Funnel Buildr, then that is not a problem as you can use Paypal/Stripe/Bluesnap within Funnel Buildr in addition to having Payment Processor A working on the main store.
7. You may also hear the term NMI. This is related to Bluesnap, and my understanding is that there are several payment processors out there who use NMI to connect. If a payment processor uses NMI then you can use them on Funnel Buildr.