Form Handlers Require Access to Base HTML of a Form

Form handlers allow you to capture data from your external website’s forms to create or update records in Salesforce. This is done by mapping Salesforce fields with your website’s fields. In order to successfully map the fields from your website's form to Salesforce, full access to the HTML of the form is required. Many form builder websites do not allow full access to the HTML of forms. Forms built by websites that do not allow full access to the HTML of the form are not compatible with Form Handlers.