FileZilla version 2 and FileZilla version 3 use different menthods and formats to store ftp account data. This program can be very useful when you need to migrate your FTP passwords and account data from FileZilla version 2 to version 3 and above.

XOR encryption is used to encode passwords. The same cypher key is always used:
FILEZILLA1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ

The encrypted password is stored in the registry or in the .xml file.
Authors of FileZilla are considering to remove encryption, but for now you have to use decoder to find your FTP account passwords.