In general, it's free to list your items for sale, but sellers may have the option to pay a nominal fee to "boost" the profile of their items, making them show up first in search results or other listings. There are a few, like eBay, which charge fees for listing an item for sale. Make sure to read the fine print before choosing to sell on an app. Other fees may include commissions or sales fees paid to the app, which can range from a flat fee to a percentage of each sale, or