At this time the primary Formstack platform is not available on the AppExchange, however, we do offer a "Formstack for Salesforce" application which is native to Salesforce and available on the AppExchange! Our Salesforce web form builder is 100% native, meaning no additional setup, connectors, or integrations are needed.
At the moment, Formstack and Formstack for Salesforce are two separate applications under the same company, therefore, separate subscriptions are required for access to their respective features.