Sigil - Sigil is a multi-platform WYSIWYG ebook editor. It is designed to edit books in ePub format.
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
Vellum - Free beautiful hand-curated wallpapers for the iPhone
Wondershare PDFelement - All-in-one PDF editor
Pressbooks - Create books: print and ebooks
Foxit Reader - Foxit Reader is a free and light-weight multi-platform PDF document viewer.