This this lib contains features to enhance Webflow's native forms.
Currently there are two primary feature-sets;
Data-binding. Initialize form fields with data, such as the current user's email address, or information from a the querystring or a cookie.
IP Info. Similar to data-binding, you can retrieve and store the users geoip information such as the country, city, and IP they're submitting the form from.
Webhook handling. Often designers want the form submission to go be sent somewhere else like a Zapier or Make interaction, or to a form handler like Basin. SA5 handles both the transmission and the response, to display the appropriate success / failure message depending on the webhook's result.