Gii, a useful tool included with Yii, allows for rapid prototyping by producing regularly used code snippets as well as whole CRUD controllers.
Gii provides a Web-based interface that allows you to produce code interactively. It also has a command-line interface for those that like to work with console windows the majority of the time.
Gii technology in Yii2 is a web-based code generator for producing models, forms, modules, CRUD, and other types of code.