You can develop free online store. There are several solutions to open it. For example, PrestaShop, WooCommerce, and others. They all are different but serve one purpose is to sell.
You need the following for the online store.
The first step in setting up your WooCommerce-powered online store is to install WordPress and the WooCommerce plugin itself. But before doing so, you should check that your hosting environment meets our minimum requirements.