A company that I worked at did this: Started as a consulting company. Made one-off web apps for businesses in a particular industry. Realized a pattern in wha

A company that I worked at did this: Started as a consulting company. Made one-off web apps for businesses in a particular industry. Realized a pattern in what these businesses wanted. Built a generic web app product. Sold the product to (and migrated) the old customers. Flourished as a product business.