CommandBox is a CLI (command line interface) package manager and automation tool for ColdFusion developers. It provides features like a package manager, REPL (read-eval-print loop), integrated server, scaffolding for frameworks like ColdBox and ContentBox, and automation commands to integrate CFML development with tasks like unit testing and source control. CommandBox aims to improve the ColdFusion development workflow and enable new use cases like packaging and distributing CFML applications and libraries.