Fantasia Archive - Free offline worldbuilding and story creation tool with dozens of templates, complex tagging options, document linking, and project-wide search. Template examples: characters, places, events, religions, currencies, magic, species, languages.

Novelize - Novelize is an online novel writing app designed to keep authors on track.

World Scribe - World Scribe is a platform that eases the creation process if novel and allows users to keep track of important elements in their world.

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.

Obsidian.md - A second brain, for you, forever. Obsidian is a powerful knowledge base that works on top of a local folder of plain text Markdown files.

Manuskript - Open-source tool for writers.