Pennywise - Cross-platform application to open any website or media in a floating window
Gumroad - An all-in-one solution to sell your work and grow your audience.
PiP for Mac - Always on top window preview similar to the popular windows only OnTopReplica
Sellfy - Sellfy is an easy to use but powerful e-commerce platform where you can sell digital, print on demand or subscription products. Use a Sellfy storefront to create a beautiful online store or embed a Sellfy shopping cart to your own website.
Shopify - Shopify is a powerful ecommerce platform that includes everything you need to create an online store and sell online. Try it free for 14 days.
Payhip - Sell digital downloads, courses, coaching, and more from one simple platform.