John the Ripper

What it is

John the Ripper is a free, open-source password security auditing and recovery tool from Openwall. It cracks many password hash and cipher types offline, with a core edition and a widely used community-enhanced “jumbo” build that adds hundreds of formats. It remains a common companion to GPU-focused crackers such as Hashcat in Hack The Box Academy and broader pentest training.

What it helps with

- Auditing password hashes obtained during authorised engagements (Unix, Windows and many application formats).
- Running dictionary, incremental and rule-based attacks against supported hashes.
- Using the jumbo build for expanded format coverage, including documents, archives and other containers where supported.
- Working across Linux, macOS, Windows and other platforms with CPU-focused and optional parallel modes.
- Pairing with Openwall wordlists and documented session/restore workflows.
- Supporting lab and training exercises on password strength under controlled conditions.

Who it's for

Penetration testers, red teams and security engineers who need offline password auditing and recovery for hashes they are authorised to process, plus students learning password-security fundamentals.

Worth knowing

Use John the Ripper only on hashes and systems you are explicitly authorised to test. Cracking credentials without permission is unlawful in most jurisdictions. The free Open Source edition is published by Openwall; commercial Pro builds also exist for some platforms. Prefer downloads and documentation from openwall.com/john and the openwall/john repository. Attribution: product framing from Openwall’s John the Ripper pages and the openwall/john README.