Customization and API

Hi, our setup is SP 2019.
Would like to know whether is it possible to customize the request membership form and the sign in form? (For branding, theme, color, more input fields etc.)
If possible, would like to have a guide on how to do so, including details such as setting the data to database.
Another reason would like to do so is because our client requires to have user profile (Have other properties such as areas of interest etc.).

And also, one more thing to check, is there any REST API available so it will ease the customization?


Yes, all can be customized. Unfortunately there is no REST api available. All changes would be on the FBA Pack source code and a copy of the built in SharePoint login page.

Branding/logo for the login page isn’t too bad, some details here:

Adding extra fields is a little more involved. You would have to modify the FBA Pack code to add the new fields. I usually save the values to the SharePoint user profile for the user. Here’s some details:

We do offer these customization services. Basic customization of the login page with a logo and links to register/forgot password can usually be done in the 4 hours included with the support plan. Adding a couple of text fields to the existing pages with no special business logic, that get stored to the SharePoint user profile, is usually around 15 hours of work.

Thanks for answering.
I am quite new to SharePoint, so just to get more clarification. When you mentioned those extra fields stored on SharePoint profile, does it mean you utilize a list where they may have a column for email and bind with other columns which will be those extra properties? So that those extra fields don’t store in membership database.

Yes, that’s correct.

Sorry to trouble. Do you have a detail guide from customizing the web part and logic, which to look for until compile and deploying the package after customizing?

Sorry, I do not. There are some posts on here, like the above, that give general guidance and some details, but no detailed guide.