Formly

Formly lets you add custom fields to your Shopify product pages so customers can provide personalized information before checkout. Add text inputs, dropdowns, and checkboxes to capture customer responses like engraving details, gift messages, or special instructions. All responses are automatically saved as line item properties and appear directly in your Shopify orders—no extra steps required. The app works seamlessly with both Add to cart and Buy it now buttons. You can assign custom fields to all products, specific products, or entire collections based on your needs.