Zend

Among the open source frameworks, Zend 1.x & 2x . is very popular.This PHP5 written. the framework is unique in terms of speed, security, utilities, libraries, ease of integration with other platforms, the web and CLI programming.

Following MVC this object-oriented web application framework provides modularity, security, extensibility and huge community support.

Modularity of Zend framework allowed it to work with other frameworks/ applications.
Cryptographic coding tools enable Zend to set things right.
Zend Framework Is extensible and gels with another framework as per needs.
This Developer friendly High Performing framework is used for high-usage applications

Yii

Yii what is YII? “Yii” stands for “Yes, it is”.
Yii an open-source web application development framework is written in PHP5.
Following MVC pattern, it is amenable to third-party code and fit for many web application development.
This free, easily extensible, adaptable and usable framework enables you to write spotless and reusablecodes.

Comparatively, Yii is comprehensive, robust and efficient.

Armed With extension library which comprises user-contributed components Yii enable you to reduce development time.

Having effective caching support and affinity to work with AJAX enables YII to process easily.

Yii is faster than other PHP based framework as it uses lazy loading technique.

Yii protects the website from three major types of attacks; XSS (Cross-Site blocking), CSRF (Cross-Site Request Forgery) and cookie attacks.

Yii has unique characteristics include Inbuilt authentication and authorization, unit and functional testing, database access object, query builder, active record, database migration and crud feature.