It checks the spelling as you type in a TextField and adds the StyleName spellcheck-error on wrong spelling. We have not defined this style in the addon, it is left for the user to do it, for example, below style makes the textbox Red on spelling error, you need to add this in your styles.css file .spellcheck-error { background-color: red !important; } It comes with preloaded dictionary with option to add few words or use a new dictionary all together, it uses jazzy library for spellcheck. http://jazzy.sourceforge.net/