BlueGriffon

BlueGriffon is a next-generation Web and EPub editor powered by Gecko, the rendering engine of Firefox. It is the successor of the Nvu editor and was developed by Daniel Glazman of Disruptive Innovations. In its latest 3.x versions users are able to create and edit pages visually or in the source view and get a professionally produced result in no time. BlueGriffon was officially recommended by the French Government as the Web authoring tool for its administration, as part of its list of recommended free software. It is accommodating for beginners all the way to pros. The core editor is free, while a paid licence unlocks extended features and some add-ons.

Features:

• BlueGriffon supports HTML5, CSS3, EPUB 3.1 and more, making it a versatile editor whose functions can be extended with add-ons.
• Creating a webpage - BlueGriffon allows you to create and edit web pages that follow web standards, switching between WYSIWYG, source and dual views, with a print preview mode, and several documents can be open in tabs.
• Adding images, links, tables, forms and colors to your page is another thing BlueGriffon does well. Elements are inserted from the toolbar and menus, and style panels let you set fonts, colors and layout with CSS.
• Audio and video can be added too. You can easily insert your audio and video files into the page or project with the HTML5 audio and video elements, directly from the toolbar icons. 

It lets beginners and advanced users edit standards-compliant web pages and EPUB books visually or in source code.

If you're looking for a standards-based visual editor, BlueGriffon suits beginners and seasoned users alike. Note that the project was discontinued by its author in 2024: the official site now shows a farewell message, and the source code is available on GitHub under the MPL 2.0 licence. The last version, 3.1, is available for Windows, macOS and Linux. Existing installations keep working, but no further updates or bug fixes will be released.