How to check if a website uses Shopify (one site or a thousand)

You have a list of online stores and you need to know which ones run on Shopify. Maybe you sell a Shopify app, run an agency, or you're building a lead list. Opening every site by hand doesn't scale past a dozen. This post covers two ways to do it: the manual check, which is fine for one site, and a bulk check that takes a list of domains and...