Overleaf - The online platform for scientific writing. Overleaf is free: start writing now with one click. No sign-up required. Great on your iPad.
LibreOffice - Writer - Open-source cross-platform word processor.
Fidus Writer - Fidus Writer is an online collaborative LaTeX editor especially made for academics who need to use...
AbiWord - AbiWord is a free software word processor.
TeXworks - The TeXworks project is an effort to build a simple TeX front-end program (working environment)...
Atlantis Word Processor - Atlantis Word Processor enables users to create documents and reports and to publish e-books.