Are there systems in place for responding to invitations?

Question

Frontend

Good afternoon!
A system for responding to invitations is needed (if I understand the name correctly).
Essence: There is a site-invitation to the event. It has a form (name, email, "I will come" button), through which people write whether they will come or not. From the functionality you need simple spam protection and import in any format. In addition to my own bike, I thought about sending it to some services such as collecting data from IoT, but this is also a crutch.
Are there any out-of-the-box solutions for not writing a bike?