PiP for Mac - Always on top window preview similar to the popular windows only OnTopReplica
Swell.is - Customizable, API-first ecommerce platform for innovative brands, startups, and agencies.
Helium - Helium lets you accept payments by credit card for anything you want to sell online.
Vendure - Open-source headless e-commerce framework for developers
X-Mouse Button Control - XMouse Button Control (XMBC) allows you to create application and window specific profiles.
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.