i3 - A dynamic tiling window manager designed for X11, inspired by wmii, and written in C.
Calendly - Say goodbye to phone and email tag for finding the perfect meeting time with Calendly. It's 100% free, super easy to use and you'll love our customer service.
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.
Acuity Scheduling - Automate your client bookings, cancellations, reminders & payments using the worlds friendliest online scheduling software.
Openbox - Openbox is a highly configurable, next generation window manager with extensive standards support.
YouCanBook.me - YouCanBook.me is a cloud-based service which allows your customers to schedule appointments and make bookings.