Why can you accept payments through Stripe (USA) through your own server, but not through PayOnline (Russia) - the merchant must have a PCI DSS certificate?

Question

Payment systems

Hello.
I'm learning how to accept payments through the site. Studied Stripe (and Braintree, but not about it now). It's a pity that Stripe doesn't work in Russia. In the dock on it I found all the answers to my questions.
Then he began to watch Russian counterparts. Came across this moment. There is our payment aggregator PayOnline.ru . From the documentation on their website ( www.payonline.ru/SDK/Net ) I realized that I can make my own payment form and place it on my website. And accept payments through your form by making a request to your server.
And here comes something that I can't understand. They write that in order to use their SDK on their server, I quote

This scheme is used if the merchant has a PCI DSS certificate.

What is it like? In my current understanding, paying through the aggregator SDK is exactly what Stripe did. And, as it seemed to me, PayOnline did it.
Why, when using Stripe, a merchant may not have PCI DSS, while PayOnline requires it?
I'm missing something somewhere. Tell me, please, who knows.

Answer 1

A PCI DSS certificate is required to accept payments on the site if you plan to process card data on your server, regardless of the number of transactions. Only the level of the certificate depends on their number.
On the Stripe website, https://stripe.com/us/features#seamless-security states that personal data is not processed on the customer's server.
If your need is to make your own form of payment and place it on your site (so that the client does not go to a separate payment page), PayOnline allows you to implement this using an Iframe.
We will gladly answer all your questions.

Answer 2

pci dss depends on the number of payments you want to accept, you can easily use the same paypal or yandex money to accept cards.