Realm Works - Realm Works is a database software and worldbuilding tool for roleplaying games.
Plot Factory - Online story planner, organizer, and writing application.
Kanka.io - Kanka.
World Anvil - World Anvil is a worldbuilding tool for Authors, Storytellers and worldbuilding lovers.
LegendKeeper - LegendKeeper makes it easy to build immersive worlds for stories and RPG campaigns.
Scrivener - Scrivener is a content-generation tool for composing and structuring documents.