For an updated list of which browsers support which HTML5 features, you can use one of the many compatibility resources provided on the web, such as this browser compatibility resource page provided by the html5rocks website.

For a list of which HTML features are supported by the GWT library, this page is the right place to look. These HTML5 features are supported by GWT:

  1. Client-side Storage – Use LocalStorage, SessionStorage, and monitor StorageEvents
  2. Canvas – Add visualizations using Canvas (Javadoc)
  3. Audio – Use Audio widgets (Javadoc)
  4. Video – Use Video widgets (Javadoc)