Dozuki - Dozuki is a web-based tool for creating and distributing step-by-step documentation.
Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.
Bloomfire - Let Bloomfire help you get organized! Organize your content, build your company knowledge base and help your employees to be more successful.
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
REWO - REWO is a knowledge documentation and distribution solution, which drastically improves capturing, visualizing and communicating knowledge.
Wondershare PDFelement - All-in-one PDF editor