Gitter is an open-source instant messaging system for users of GitHub. It has a free option that provides all basic features like private chat rooms. Like Slack, Gitter saves all messages in the cloud.
Web page: gitter.im
PDF (Portable Document Format) is a commonly used document format created by Adobe. Creating a PDF of a keyboard shortcut list may make it easier to print, quicker to open, and view offline. The PDF output is also without any ads, it's just the basic list presented in two or three columns.
Printing notice: Please consider environmental effect before printing on a paper.