Yii

Yii is a high-performance open-source PHP framework for developing web applications. It follows the model–view–controller (MVC) pattern and emphasizes speed, reusability, and extensibility. The name Yii is commonly described as standing for “Yes It Is,” reflecting its aim of being easy to use for rapid development.

Yii was created by Qiang Xue and first released as Yii 1.0 in 2008. A complete rewrite, Yii 2.0, arrived in 2014 with modern PHP features, namespace support, and Composer-based installation; it remains the active development line. A future Yii 3 is being pursued to further modernize the framework and align with evolving PHP standards.

Key features of Yii include an Active Record ORM and a data access layer, a powerful code generator (Gii) for rapid CRUD scaffolding, a rich set of widgets and extensions, and built-in support for caching, authentication, and authorization. The framework provides RESTful API support, URL management with pretty URLs, internationalization, theming, and robust testing tools, along with security features such as input filtering, CSRF protection, and XSS prevention.

Yii is used to build a wide range of web applications, from small projects to large-scale systems and API backends. It has an extensive extension ecosystem and a dedicated community. Yii is released under the BSD license and is available via Composer, making integration with other PHP libraries straightforward.