This is a short list of 20 popular free apps for the Shopify eCommerce platform. I scraped the data for a proposal to one of my clients, which led to a dramatic boost in her sales.
Source: https://www.shopify.co.uk/blog/12206421-the-top-20-most-popular-free-apps-in-the-shopify-app-store
I am not affiliated with Shopify in any way, all credit goes to the original author(s).