Below is a table that lists all available Zend Framework Components and which PHP extension they need. This can help guide you to know which extensions are required for your application. Not all extensions used by Zend Framework are required for every application.
A dependency of type "hard" indicates that the components or classes cannot function properly if the respective extension is not available, while a dependency of type "soft" indicates that the component may use the extension if it is available but will function properly if it is not. Many components will automatically use certain extensions if they are available to optimize performance but will execute code with similar functionality in the component itself if the extensions are unavailable.
Table 173. Zend Framework Components and the PHP Extensions they use