Cloudfail
Console-based

CyberChef
https://gchq.github.io/CyberChef
Webserver-based

SubDomain Analyzer
https://github.com/El3ct71k/SubDomain-Analyzer
Console-based tool to analyze target domains.

nano-syntax
Syntax highlighting support for the nano text editor.
Installing nano provides the editor itself.
Installing nano-syntax (or enabling syntax configs) adds colorized highlighting for programming and scripting files.

tmux
Terminal multiplexer (released 2007).
Designed to address limitations of GNU Screen (released 1987).
Supports panes, windows, mouse interaction, UTF-8, and scripting.
Widely preferred on Red Hat, Fedora, CentOS, and Oracle Linux.
Commonly available by default in rescue shells and minimal installs.

bash-completion
Shell completion framework for Bash.
Pressing Tab shows or completes commands, options, flags, and paths.
Commonly enabled by default in Kali Linux and other security-focused distros.
Helps discover command options and improves speed and accuracy at the terminal.