Grapevine Surveys is a Shopify app that allows you to create post-purchase surveys for both new and returning customers. With Grapevine, you can collect valuable insights and monitor ad performance by gathering zero-party data from your customers. The app offers various survey options, including HDYH, multiple choice, and NPS. You can use this information to optimize your marketing spend and determine the most effective channels for customer acquisition. Grapevine also tracks survey submissions and their associated sale values, allowing you to analyze performance against spend.