Looking for a solution: external facing form -> create new objects associated with a contact

Anyone out there know of a solution for external facing forms to create new objects associated with designated contacts?

When I first started my org was using Form Assembly but it was unreliable and required entering the 22 digit Contact ID that our volunteers had a lot of trouble with. Currently we're using Smartsheet to collect data on how folks are engaging in our services but the data never gets associated back to the contact in Salesforce.

#forms