What are some alternatives?
MadCap Flare - Documentation for Any Audience, Language or Format
Bloomfire - Let Bloomfire help you get organized! Organize your content, build your company knowledge base and help your employees to be more successful.
Adobe RoboHelp - Adobe RoboHelp empowers organizations to deliver engaging help and policy content across mobile devices, formats, and platforms.
Communifire - Enterprise Social Collaboration Software
Dr.Explain - Dr.Explain software is a help file authoring tool.
Quip - Quip is the modern productivity suite that simplifies your life and helps your team get work done faster.