Website Builder
Free · Open
A cross-platform WYSIWYG web and EPUB editor based on the Firefox rendering engine, supporting HTML5, CSS3, and SVG editing
Website Builder·Ebook Editor
Desktop
AlertCaution is advised.

Free · Open
Quickly generates static websites from content written in Markdown or other formats by passing the content through user-defined templates
Static Site Generator·Website Builder·Blog Publishing System
Desktop
AlertCaution is advised.
Paid
Visual web editor for professionals, integrates with HTML, CSS, Bootstrap, WordPress, and more
Website Builder
Desktop
AlertCaution is advised.