Gii is a code generator of Yii2. From the article 

Pros

• CRUD code is generated for each model/table, which you can subsequently change as you like.
• You don’t need to follow the ideology of the ready-made library and are free in your work.
• There are a sufficient number of ready-to-use frontend components in the framework itself.

 Gii is a code generator of Yii2. From the article 

Pros

• CRUD code is generated for each model/table, which you can subsequently change as you like.
• You don’t need to follow the ideology of the ready-made library and are free in your work.
• There are a sufficient number of ready-to-use frontend components in the framework itself.