Why Should we Use an Online HTML Editor?
The best thing about online HTML editors is that they'll run directly in your web browser. Your web browser is the best and most relevant tool for processing and rendering HTML code. That is, after all, its entire purpose and reason for being.
An online HTML editor can dynamically refresh itself as you write and change the markup. There is no need to flip back and forth between windows. You tweak the HTML on one side, the changes automatically occur on the other side.
Online HTML editors are as portable as they come. No matter what machine you’re on, you can access the web editor as long as you have an internet connection. No need to install and configure a standalone editor that you may or may not use again.
Here's The List :
Liveweave is similar to the previous editor above, with an interface that’s more pleasing to the eye (though your preferences may vary). Like JSFiddle, Liveweave allows for real-time collaboration, and like JSBin, it lets you link in predefined third-party resources like jQuery.