i3 - A dynamic tiling window manager designed for X11, inspired by wmii, and written in C.
PayPal - PayPal is the faster, safer way to pay online without sharing financial details, send and receive money or accept credit and debit cards as a seller
dwm - dwm is a dynamic window manager for X. It manages windows in tiled, monocle and floating layouts. All of the layouts can be applied dynamically, optimising the environment for the application in use and the task performed.
Stripe - Online payment processing for internet businesses. Stripe is a suite of payment APIs that powers commerce for online businesses of all sizes. Use Stripe’s payment platform to accept and process payments online for easy-to-use commerce solutions.
Openbox - Openbox is a highly configurable, next generation window manager with extensive standards support.
Braintree - An all-in-one solution to accept, process, and split payments in your mobile app or online - from small business to large enterprise.