Kali is a complete rebuild of BackTrack Linux and adheres to all Debian development standards. All new infrastructure was created, all tools were reviewed, packaged, and we use Git as our VCS.
More than 300 penetration testing tools: BackTrack was able to review every tool and eliminate any that did not work or were compatible with other tools.
Kali Linux is free and will always be free: Kali Linux, just like its predecessor, will always be completely free. Kali Linux will not ever require you to pay anything.
Open source Git tree : We are big supporters of open source software. Our development tree is accessible to all and all sources are available to those who wish to modify and rebuild packages.
FHS compliant: Kali was developed to conform to the Filesystem Hierarchy Standard. This allows all Linux users to locate binaries, support and libraries easily.
We offer vast wireless device support: Kali Linux has been designed to work on many different types of wireless devices and is compatible with many other USB devices.
Custom kernel patched to inject: The development team is often required to conduct wireless assessments in order for our kernel to have the most recent injection patches.
Secure development environment: The Kali Linux Team is comprised of a small group trusted individuals who can only interact with the repositories and commit packages while using multiple secure protocols.
GPG signed packages, repos: All Kali packages are signed individually by the developers when they are created and committed. The repositories then sign the packages.
Multi-language: While pentesting tools are often written in English, Kali offers true multilingual support. This allows more users to use Kali in their native language to locate the tools and tools they need.
Completely customizable: We understand that not all users will agree with our design decisions. Therefore, we made it as easy for our more adventurous users as possible to customize Kali Linux to suit their needs, right down to the kernel.
Kali is designed for penetration testing. All documentation on this site assumes that you have some knowledge of the Linux operating systems.
Differences between Kali Linux and Debian
Kali Linux is designed for professional penetration testing and security auditing. These needs have been reflected in several core changes to Kali Linux:
By design, Kali Linux is intended to be used as a single user with root access.
Network services disabled by default: Kali Linux has sysvinit Hooks that disable network services by default. These hooks allow us install many services on Kali Linux while also ensuring that our distribution is secure by default, regardless of what packages are installed. Additional services like Bluetooth are also blacklisted by default.
Kali Linux uses a custom Linux kernel. This upstream kernel is patched for wireless injection.

Is Kali Linux Right For You?
One would expect distribution developers to recommend Kali Linux to everyone. Kali Linux is a Linux distribution that is specifically designed for professional penetration testing and security auditing. As such, it is not recommended for people who are unfamiliar with Linux.
Additionally, misuse of security tools within your network without permission can cause irreparable damage, and could have serious consequences.