HTML to WordPress is described as 'Quickly convert an HTML web site into a WordPress theme with a super-simple drag-and-drop process' and is an website in the Development category. There are four alternatives to HTML to WordPress, not only websites but also apps for a variety of platforms, including Wordpress, Sass, Self-Hosted solutions and SaaS. The best alternative is Pinegrow Web Editor. It's not free, so if you're looking for a free alternative, you could try Hadron. Other great sites and apps similar to HTML to WordPress are Udesly (Paid) and HTML To WordPress Converter (Paid).
Pinegrow is a Mac, Windows and Linux web editor that lets you build responsive websites faster with live multi-page editing, CSS & SASS styling, CSS Grid editor and smart components for Bootstrap, Foundation and WordPress.
HTML To WordPress converter is a WordPress plugin that allows you to convert a plain html theme into WordPress theme, without any knowledge of coding, it only requires some knowledge of HTML and how WordPress theme works.