JSFiddle

JSFiddle is an online HTML editor which comes with some amazing features. It is a minimal HTML editor with a live preview feature. This online HTML editor supports HTML, CSS, and JavaScript.

Talking about the features, JSFiddle allows you to select different types of language to edit or write code in. For example, there are document type options like HTML 5, XHTML 1.0 Strict, and HTML 4.01 Transitional etc, which you can choose if you are editing in HTML panel.

Secondly, its JavaScript support allows you to load the library. Code snippets in JSFiddle are termed as fiddles.
Overall JSFiddle is easy to use, has JavaScript support, and is a free HTML editor.