Ask HN: Any recommended third party sign-up service?

Hello HN,

What third party service would you recommend to have a smooth and visually attractive sign up process for users? The service should be able to submit the sign up elements to a webhook API (no sensitive info is shared at that point).

I am currently using Typeform for GetMyMFA (https://get.mymfa.io) but unfortunately there is a maximum of 10 monthly questions and paying 20 bucks per month for « only » 100 sign ups is definitely excessive.

Thanks in advance!