The Kali Linux operating system comes pre-installed with around 600 penetration testing programs (tools), including Armitage (a graphical cyber attack management tool), NMap (a port scanner), Wireshark (a packet analyzer), Metasploit (a penetration testing framework, as the best penetration testing software), John Ripper (password generator), Squallmap (automated SQL injection and database capture tool), Aircrack-ng (software suite for wireless network penetration testing), Burp suite and security scanners OWASP ZAP web application etc.

Kali was developed by Matti Aharoni and Devon Kearns of Offensive Security by rewriting the Linux code of Backtrack, an earlier information security testing Linux distribution based on Knopix. Backtrack itself emerged from the merger of two previous competing versions of Linux. Originally, it was designed with a focus on kernel auditing, hence the name Audited Linux Kernel. The name is sometimes mistakenly believed to be derived from the Hindu goddess Kali. Third core developer Raphaël Hertzog joined them as a Debian expert.

Kali Linux is based on the Debian test branch. Most of the packages Kali uses are imported from the Debian repositories.

Kali Linux's popularity increased when it was featured in several episodes of the TV series Mr. Robot. Tools featured in the demo and provided by Kali Linux include Bluesniff, Bluetooth Scanner (btscanner), John the Ripper, Metasploit Framework, Nmap, Shellshock, and Wget.