Yii is an open source, object-oriented, component-based MVC PHP web application framework. Developed by Yii Software LLC
License: Open Source
Yii Framework is designed for high-performance applications with a robust set of features and strong community support, while Kohana is a lightweight framework that is easier to learn and use but lacks some advanced features and community backing. Yii is better for larger, complex projects, whereas Kohana may be more suited for simpler applications.