Do you need a free web editor that supports HML5? I needed one and I really had to waste some time to review some. Here are the conclusions (and the conclusions only). NOTE: See the 2017 update at the end of the post!
BlueGriffon
2015
Price: Free or 70 euros: http://www.bluegriffon.org/#whatsinside
Comment: Seems robust and mature
Maqetta
Discontinued may 2013, but still online
Price: free
Kit size: 86MB
Conclusion: Difficult to Install. Needs Java 6!
LibreOffice
2015
Price: free
OpenOffice.org 2014
It only has a web page editor (not web site builder)
Dreamweaver 2015
Conclusion: Nice but way too expensive!
Microsoft Expression 2012
(discontinued)
openElement 2014
Free
Kits size: 47MB
oXygenXML Editor 2015
Conclusion: not tested yet
TOWeb 2013
Conclusion: not tested yet
WebStorm IDE 2013
Conclusion: not tested yet
Based on: https://en.wikipedia.org/wiki/Comparison_of_HTML_editors
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UPDATE 2017
Stormy Website Builder is the ultimate tool for building a web site (CMS). It has a beautiful WYSIWYG html editor. You can have a site up an running in only 4 minutes.
Stormy Website Builder wants to be a lightweight alternative for Joomla CMS.