Hashcat is a GPU-based cracking engine designed for brute-force and dictionary attacks using rules and filters. It is designed to target password hashes and is considered to be the fastest method for password cracking. Useful with a hash that does not pass, or when auditing password strength based on a collection of hashes. It comes pre-installed in Kali and Parrot OS.

In addition to Hashcat, also download a wordlist like the 10-million-password-list-top-100.txt or rockyou.txt. It contains a list of commonly used passwords and is popular among pen testers. You can find the Rockyou wordlist under /usr/share/wordlists in Kali Linux.

And the mode (-m) for the type of hash.

For example, the hash mode value for SHA1 is 100, and for doing a dictionary attack (-a 0):

$ hashcat -m 100 -a 0 sha1.txt /usr/share/wordlists/rockyou.txt