WikiExt is described as 'com is a large database storing more than 15 000 file types. Wiki Ext will help you open any file extension!'. There are three alternatives to WikiExt for Online / Web-based, Windows and Windows Explorer. The best alternative is FileInfo.com, which is free. Other great apps like WikiExt are OpenWith.org (Free) and File-Extensions.org (Free).
FileInfo.com contains a searchable database of thousands of file extensions with detailed information about the associated file types. You can use FileInfo.com to lookup information about unknown file types and find programs that open the files.