bibisco - bibisco is a novel writing software.
Novelize - Novelize is an online novel writing app designed to keep authors on track.
Manuskript - Open-source tool for writers.
WriteFreely - Write Freely is free and open source software for starting a minimalist, federated blog — or an entire community.
BlankPage - Stay motivated to write, and finish your story
Nulis - Tree editor for writers, makes outlining your stories and articles easy, fun, and convenient.