Twurdy uses text analysis software to "read" each page before it is displayed in the results. Then Twurdy gives each page a readability level. Twurdy then shows the readability level of the page along with a color coded system to help users determine how easy the page will be to understand.
VOICE, the Vienna-Oxford International Corpus of English, is a structured collection of language data, the first computer-readable corpus capturing spoken ELF interactions of this kind.