Seequill is described as 'Online story-writing platform. Free for offline use. Only $30/year for full features. Organize your stories, track characters and locations. Groundbreaking plot interface' and is an website in the News & Books category. There are more than 10 alternatives to Seequill, not only websites but also apps for a variety of platforms, including Windows, Mac, Linux and iPhone. The best alternative is Manuskript, which is both free and Open Source. Other great sites and apps similar to Seequill are Scrivener (Paid), bibisco (Freemium, Open Source), yWriter (Freemium) and True Novelist (Free).
Manuskript is an open-source tool for writers, with outliner, character management, plot development, distraction-free editor, etc. Outliner Organize your thoughts and snippets in a hierarchical manner. Organize them as you wish, reorganize them on the go.
yWriter is a writing tool that uses "scenes" as a unit of text and allows you to associate that text with all manner of story elements (characters, locations, items) as well as place it and rearrange it within the context of chapters.
The writer’s choice of novel-writing tool. Online & offline, desktop and mobile. Chapter/scene organisation; version history; analytics & goals; advanced grammar check; export & publish to epub...everything you need to support your novel-writing.
A most awesome writing tool Create novels, short stories, research papers, notes. Track progress on individual documents and your entire project. Relate documents and items to people, places, plot points and actions.
A document manager and site builder/generator for Word users. You can open Word documents in tabs, manage documents on a project basis, full-text search documents across multiple project folders, attach tags, notes, stars, and so on to the documents.