LibreOffice - Writer - Open-source cross-platform word processor.
StoryMill - Developers and publishers of Mac, Win, and iOS productivity, home and office and writing software such as MacGourmet, Paperless and many more. Based in MN.
AbiWord - AbiWord is a free software word processor.
Novelize - Novelize is an online novel writing app designed to keep authors on track.
Atlantis Word Processor - Atlantis Word Processor enables users to create documents and reports and to publish e-books.
Manuskript - Open-source tool for writers.