When comparing Slim vs Zend Framework, the Slant community recommends Slim for most people. In the question“What are the best PHP frameworks?” Slim is ranked 1st while Zend Framework is ranked 18th. The most important reason people chose Slim is:
Slim's documentation is well organized and detailed, every concept is thoroughly explained and it is very helpful for both advanced users and beginners.
Specs
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Pros
Pro Well organized and thorough documentation
Slim's documentation is well organized and detailed, every concept is thoroughly explained and it is very helpful for both advanced users and beginners.
Pro A good starting point
Slim is minimal and that is a good thing if you want to start from there. It can be easily extended and even supports popular packages that are used in Laravel (like Illuminate\Database (eloquent)) for example.
Pro REST based
REST fans will love the REST based architecture.
Pro Supports tie-ins for Rack-like middleware
Rack is an interface used in Ruby frameworks used to group and order modules, which most of the time are Ruby classes, and specify between them.
Slim uses a simple concept for it's middleware. By wrapping HTTP requests and responses it unifies the middleware into a single method call.
Pro Useful classes
Contains classes for managing requests, responses, cookies, logging, views, HTTP caching, and more.
Pro Flexible
Slim doesn't demand that you stick to a fixed folder structure. As long as you load Slim the right way you can do anything from there the way you like it.
Pro Extremely lightweight
Paired with swoole it's a micro service powerhouse.
Pro Open source
The Slim Framework is open source and is released under the MIT public license
Pro Extremely customizable
You can add any dependency, package or class that you want to use as a contained dependency.
Pro Supports Php 5.3 and PHP 7
Pro Makes it easy to understand the way some abstract functions and classes are built
In Django most things are abstracted, you just call some function or class without knowing how they were built, but with Slim, you end up understanding the way some abstract functions and classes are built.
Pro Hooks for executing code at different points in its life-cycle
Slim supports code hooks for executing functions at different points in time during the application's lifecycle.
Pro Well architected
Pro Enterprise ready
Zend is the most used PHP framework by big businesses. Zend is widely used and tested by a large number of banks, as well as companies, such as Allied Beverage, BBC, Shaklee, CarinBridge, BNP Paribas and more.
Pro Corporate backing
Partnered with Google, IBM, Adobe, Microsoft
Pro Extended predefined classes
Zend has a large library of predefined classes with which developers can create maintainable and stable web applications. This is done if the developer works within the constraints and with the components of these different predefined classes, which makes the application more maintainable.
Pro Wide database support
Zend supports almost all kinds of databases out there. From MySQL, IBM DB2, Oracle, Microsoft SQL Server to PostgreSQL.
Pro Allows customization
For developpers not used to Zend, they can use a predefined structure and use preloaded components and classes to build and maintain their application. But for advanced developpers, they can customize the structure to stick to their needs (or their likings) and extend primary Zend components for fine-tuned apps or replace the initial predefined Zend components by third parties components such as Doctrine ORM or another logging or templating framework.
Pro Easy to build an API with Apigility
Apigility is a collection of Zend Framework modules. It's useful for building the API architecture of a web app quickly and painlessly by providing a flexible engine.
Apigility also has a web-based UI that allows developers to quickly create and modify API services, configure authentication, set authorization rules, set up validation and write new documents.
Cons
Con Very little consistency among different versions
There have been quite some changes that break the compatibility between Slim 2 and Slim 3. Even if you learned how to work with the Slim 2, you will find that Slim 3 requires re-training.
Con Dependency injection is too weak
It is not really dependency injection, but just a configurable container.
Con Needs strong bases to create dependencies
The dependency container schema of Slim is one of the biggest PROS and CONS of the framework. It is true that this schema brings so much flexibility to add anything, but another thing that is true is that you need to have strong bases of patterns, and an extensive knowledge of your libraries to convert it into a Slim dependency.
Con Too minimal
While it's true that Slim is a microframework, it's still too minimal. When used for throwaway projects or simple prototypes, it's perfect. But in the long run, it becomes less and less useful and you end up in implementing a full custom framework in trying to tackle all the missing features.
Con Loose documentation
Since Zend has a loosely-coupled architecture, it means that the documentation will be quite loose as well. Even though there's a lot of documentation for the framework, it's still hard to use it as a guideline to create a completed project. Although this can be less of a problem considering all the tutorials and guides out there.
