In addition to the built in features, some browsers allow you to add extra features by the use of plugins. CWS find the following plugins handy for checking accessibility and validation on websites

Firefox plugins

• Firebug - Free
  http://getfirebug.com/

• Total Validator - Free
  https://addons.mozilla.org/en-US/firefox/addon/2318

• Web Developer Toolbar - Free
  http://www.paciellogroup.com/resources/wat-about.html

Opera plugins

• Web Accessibility Toolbar - Free
  http://www.paciellogroup.com/resources/wat-about.html