What is “vnu” Package?

Nu Markup Checker: command-line and server HTML validator
For more details: https://validator.github.io/validator/

Installation

• Open Terminal by pressing command+space then type terminal and hit Enter key.
• Install homebrew first.

  ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null

• Install vnu.

  brew install vnu

Now, use vnu!