KHTML
KDE HTML widget
This library provides a full-featured HTML parser and widget. It is used for rendering in all KDE applications which allow HTML viewing, including the Konqueror browser/file manager, KMail, and the KDE Help system.
This library provides support for HTML4/XHTML, embedded Java applets, cascading style sheets (CSS2), and JavaScript.
If you want to add to your application a widget that only needs simple text browsing, you can also use the KTextBrowser widget in kdeui.