Chef is a company and the name of a configuration management tool written in Ruby and Erlang. It uses a pure-Ruby, domain-specific language for writing system configuration "recipes".

What is chef tool used for?

Chef is used to streamline the task of configuring and maintaining a company's servers, and can integrate with cloud-based platforms such as Amazon EC2, Google Cloud Platform, Oracle Cloud, OpenStack, IBM Cloud, Microsoft Azure, and Rackspace to automatically provision and configure new machines.

Is Chef free software?

Chef is open source, you can use if for free, and they have good on-line documentation and wiki pages. Chef has several 'flavors'. You can run the whole thing for free using Chef-Server (which requires you to set up the server software in addition to the client software on your system).