Storybook is a Libre Software for writers, essayists, authors. Used from the draft to the final work, with oStorybook you can never lose the history of the field of view.
Please visit oStorybook.eu for more informations.
You don't have to register to use oStorybook. On the other hand, if you want to ask a question on the help forum, you will have to register an account. This is simply because some people regularly try to hack this site (I don't see any valid reason to do that except to harm others).