What are the payment systems that generate payment widgets on the site with several options for amounts?

Question

CMS

Good time! There is a site about the upcoming conference, assembled on the weebly.com constructor. You need to make a registration form with 4 options for the cost of participation, which would redirect the visitor to some payment system. Restriction: this site does not allow you to add your code to the web server, but you can embed your Javascript and html code anywhere on the page.
Question: what payment services / aggregators exist that allow you to generate the html code of a certain widget with predetermined amounts for payment? It is necessary that this widget shows a form for selecting the amount and proceeding to payment. And it is desirable to allow the user to pay for participation in the conference in various ways (by card, Yandex.money, etc.).

Answer 1

https://2event.com/uk/
ticketforevent.com/en/mail
These are not payment systems, but services that allow you to sell tickets for your events, and you can keep several prices there