Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
Gumroad is a self-publishing digital marketplace platform to sell digital services such as books, memberships, courses and other digital services.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Squarespace Commerce is an ecommerce platform designed to facilitate the creation of websites and online stores, with domain registration and web hosting included.
Squarespace provides Software-as-a-Service (SaaS) for website building and hosting, and allows users to use pre-built website templates.
Typekit is an online service which offers a subscription library of fonts.