LibreOffice - Writer - Open-source cross-platform word processor.
Overleaf - The online platform for scientific writing. Overleaf is free: start writing now with one click. No sign-up required. Great on your iPad.
AbiWord - AbiWord is a free software word processor.
TeXstudio - TeXstudio is an integrated environment for writing LaTeX documents.
Atlantis Word Processor - Atlantis Word Processor enables users to create documents and reports and to publish e-books.
LyX - LyX is a document processor.