KDiff3 is a program that

    * compares and merges two or three input files or directories,
    * shows the differences line by line and character by character (!),
    * provides an automatic merge-facility and
    * an integrated editor for comfortable solving of merge-conflicts
    * has support for KDE-KIO (ftp, sftp, http, fish, smb)
    * and has an intuitive graphical user interface.