> Unless you're using a plugin like Stripe's for every processor, quickly doing a request to your processor directly in the user's browser and submitting each of the tokens to yourself, doing this would require you to at least accept and transmit credit cards yourself, not sending the consumer onto the processor's site to fill it out. You are now transmitting credit card data yourself, which means you'll have to go through the PCI Compliance process. It's a self-assessment, and you can skip a lot of steps if you're at least not storing the card number (which you probably should not), but it still a bit of an arduous process. No one's going to check you on this unless there's some sort of breach, but you should still definitely do it.

This is the biggest hurdle to tokenizing at multiple providers by far. As soon as you actually "touch" that credit card number (not Stripe/etc's SDK or iFrame) everything changes. Also the PCI Compliance process is a bitch and a half and is confusing as fuck. For me it was a janky web-app form that was not clear and lead to me answering wrong multiple times then being very confused at the questions it was asking me (I had to call in and their support knew the pitfalls and were able to steer me back but the instructions/question-wording is terrible).