John the Ripper is a Scripts software developed by Alexander Peslyak. After our trial and test, the software is proved to be official, secure and free. Here is the official description for John the Ripper:

BSEditor: John the Ripper is a fast Password Cracker, Currently available for many flavors of Unix, Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to Detect weak Unix passwords. Besides several Crypt(3) password hash types most commonly found on various Unix systems, supported out of the box are Windows LM hashes, plus many more with contributed patches.

John the Ripper is free and Open Source software, distributed primarily in source code form. If you would rather use a commercial product tailored for your specific operating system, please consider John the Ripper Pro, which is distributed primarily in the form of "native" packages for the target operating systems and in general is meant to be easier to install and use while delivering optimal performance.