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For other uses, see YII (disambiguation).
Yii logo
Stable release 2.0.6[1] / August 5, 2015 (2015-08-05)
Development status Active
Written in PHP
Operating system Cross-platform
Type Web application framework
License New BSD License
Website www.yiiframework.com

Yii is an open source, object-oriented, component-based MVC PHP web application framework. Yii is pronounced as "Yee" or [ji:] and in Chinese it means "simple and evolutionary" and it can be acronym for "Yes It Is!".[2]


The Yii project was an attempt to fix some drawbacks of the PRADO framework. For example, in its early versions PRADO was slow when handling complex pages, had a steep learning curve and many controls were difficult to customize, while Yii was much more efficient at that time. In October 2006, after ten months of private development, the first alpha version of Yii was released. On December 3, 2008, Yii 1.0 was formally released.

January 2010 Yii 1.1 was released featuring form builder, relational ActiveRecord queries, unit testing framework and more. At the end of 2010 feature list for Yii 1.2 was on internal discussion. In May 2011 team decided to use new PHP versions and fix architectural mistakes. That basically meant 2.0. Same month the first commit was made. In May 2013 Yii 2.0 code went public. In October 2014 the first stable release of Yii 2.0 happened.


Yii features include:

  • Model-View-Controller (MVC) design pattern.
  • Generation of complex WSDL service specifications and management of Web service request handling.
  • Internationalization and localization (I18N and L10N). It supports message translation, date and time formatting, number formatting, and interface localization.
  • Layered caching scheme. It supports data caching, page caching, fragment caching and dynamic content. The storage medium of caching can be changed.
  • Error handling and logging. Errors are handled and presented more nicely, and log messages can be categorized, filtered and routed to different destinations.
  • Security measures include cross-site scripting (XSS) prevention, cross-site request forgery (CSRF) prevention, cookie tampering prevention, etc.
  • Unit and functionality testing based on PHPUnit and Selenium.
  • Automatic code generation for the skeleton application, CRUD applications, etc.
  • Code generated by Yii components and command line tools complies to the XHTML standard.
  • Carefully designed to work well with third-party code. For example, it's possible to use code from PEAR or Zend Framework in a Yii application.

Version history[edit]

Color Meaning
Red Old version; no longer supported
Yellow Old version; still supported
Green Current version
Blue Future version
Version Release Release date End of maintenance[3] Requirement[3]
1.0 1.0 December 3, 2008 December 31, 2010 PHP 5.1.0 or above
1.0.1 January 4, 2009
1.0.2 February 1, 2009
1.0.3 March 1, 2009
1.0.4 April 5, 2009
1.0.5 May 10, 2009
1.0.6 June 7, 2009
1.0.7 July 5, 2009
1.0.8 August 9, 2009
1.0.9 September 6, 2009
1.0.10 October 18, 2009
1.0.11 December 13, 2009
1.0.12 March 14, 2010
1.1 1.1.0 January 10, 2010 December 31, 2015 or later PHP 5.1.0 or above
1.1.1 March 14, 2010
1.1.2 May 2, 2010
1.1.3 July 4, 2010
1.1.4 September 5, 2010
1.1.5 November 14, 2010
1.1.6 January 16, 2011
1.1.7 March 27, 2011
1.1.8 June 26, 2011
1.1.9 January 1, 2012
1.1.10 February 12, 2012
1.1.11 July 29, 2012
1.1.12 August 19, 2012
1.1.13 December 30, 2012
1.1.14 August 11, 2013
1.1.15 June 29, 2014
1.1.16 December 21, 2014
2.0 2.0.0 October 12, 2014 TBD PHP 5.4.0 or above
2.0.1 December 7, 2014
2.0.2 January 11, 2015
2.0.3 March 1, 2015
2.0.4 May 10, 2015
2.0.5 July 11, 2015
2.0.6 August 5, 2015


The Yii project has an extension repository consisting of user-contributed components.

There was also an official extension library, zii, which was then merged with the core framework. It is bundled in every release since Yii version 1.1.0, and it includes additional behaviors and widgets, such as grids and jQuery UI.


Yii comes with a collection of official documentation, such as a tutorial to develop a simple blog application, a guide that gives the description of every feature and a class reference which gives every detail about properties, methods and events.

There's also a user-contributed documentation, most of which is available within the wiki on the official website.


Yii is released under the New BSD License (3-clause license). This means that it's possible to use it for free to develop either open-source or proprietary Web applications.

The text contained in the Official Yii Documentation is licensed to the public under the GNU Free Documentation License (GFDL). In general, the Yii documentation content can be copied, modified, and redistributed so long as the new version grants the same freedoms to others and acknowledges the authors of the Yii documentation article used.[4]

The logo is licensed under a Creative Commons Attribution-No Derivative Works 3.0 Unported License.[5]




  • Behme, Henning (January 2009). "World Wide Web". iX (Heise). 
  • Winesett, Jeffrey (March 2009). "Adding the Yii Framework to Your Web Development Toolbox". php|architect. 
  • Winesett, Jeffrey (July 2009). "Yii: Flex Your Flash". php|architect. 
  • Kreußel, Peter (November 2009). "PHP-Frameworks im Überblick, Viel Holz für den Rahmen". Linux-Magazin (Linux New Media AG). 
  • Setter, Matthew (December 2010). "YiiLocal – Find Stuff Near You". php|architect. 
  • Moorjani, Philip (April 2014). "Introduction to Yii 2.0". php|architect. 

See also[edit]


  1. ^ "Yii 2.0.6 is released". Yiiframework.com. 2015-08-05. Retrieved 2015-08-06. 
  2. ^ "About Yii". Yii2 Guide. yiisoft. 
  3. ^ a b "Download Yii Framework". Retrieved 18 January 2011. 
  4. ^ "Terms of the Yii Documentation". Retrieved 22 August 2010. 
  5. ^ "Official Logo". Retrieved 20 October 2010. 

External links[edit]