FileZilla FTP client stores passwords in plain text.

FileZilla FTP client by default silently stores all entered FTP usernames and passwords in plain text.
Passwords may be stored in following locations.
Path:
Windows XP: C:\Documents and Settings\user.name\Application Data\FileZilla
Windows Visata/7: C:\Users\user.name\AppData\Roaming\FileZilla
Files:
recentservers.xml
sitemanager.xml
filezilla.xml

To disable this default behaviour:
1. Copy file C:\Program Files\FileZilla FTP Client\docs\fzdefaults.xml.example to C:\Program Files\FileZilla FTP Client
2. Rename file to fzdefaults.xml
3. Open file in text editor and change set <Setting name=”Kiosk mode”>1</Setting>
4. Comment line: <!–<Setting name=”Config Location”>$SOMEDIR/filezilla/</Setting>–>. Or set desired config file location if you wish.
You can also set <Setting name=”Disable update check”>1</Setting> to disable update check.
5. Save and close the file
6. Delete or rename existing files containing passwords (see above for file names and path)

FileZilla 3.3
Windows XP, Vista, 7