[TrianguloY]

I personally use Google forms for a very similar feature. You don't even need to display the google form itself, you can create your own and then perform a fetch.

I even have it connected to a google sheet and google scripts, to send me emails for entries matching some patterns.

Heavily depends on Google, yes, but for something free that honestly I won't care if stops working (like a prototype) I'm ok with it.