Your store lets you offer extras like engraving, a gift message, gift wrap or a rush upgrade, but it treats every one of them as free. There is no price field anywhere. Merchants who want to charge end up building fake product variants, which wrecks their stock counts, or they give the work away.
Modifier Pricing adds the price. Create an add-on once, a text box for engraving, a list for wrap choices, a colour swatch, or a simple yes or no. Give each choice its own amount. Attach it to as many products as you like.
Applying it takes one action instead of an afternoon. Tick the products you want, or select your whole catalogue, and see exactly how many will change before anything happens.
Shoppers see the add-on on your normal product page. There is nothing to place in the editor and no code to add. When someone picks a paid extra, the amount appears as its own line on their cart and checkout, and on your order.
Your Add to Cart button is never replaced and your checkout is never intercepted. Options that track stock stay where they belong, on the variant, so your inventory keeps working exactly as it does today.
A free plan is included. Upgrade when your catalogue grows.