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 need to register an account. This is simply because dishonest people regularly try to hack into this site (I can't think of any valid reason for doing this other than to harm others).
oStorybook one of the best software for writers
oStorybook is Free Software for writers, essayists and authors. Used from draft to finished work, oStorybook ensures that you never lose sight of the storyline. oStorybook helps you keep control of the various developments in your story.
oStorybook is the successor to Storybook, an original creation by Martin Mustun. While the source code of Martin's last published version was partly hidden, all the current code is now freely accessible.
oStorybook helps you structure your work
Characters, locations, scenes, objects, reference points and ideas are all managed in a single, coherent package. A simple interface lets you define each element and each scene, while maintaining a permanent overview of your work thanks to easy-to-understand, practical tools. Memoria, for example, lets you visualize the links between each component and the others.