There is only one file type that uses the .WTF extension:
World of Warcraft Text File
Text file used by World of Warcraft (WoW) to save various game settings; for example, Config.wtf saves audio and display settings; Realmlist.wtf stores realms in which players can play on different private servers.
WoW settings can be modified by opening and editing WTF files in a text editor. Make sure to backup the WTF file before editing it since incorrect changes may corrupt the file.
Updated: May 30, 2008