CodeIgniter vs Silex

Setting up CodeIgniter is quick and easy. You can download the version you want from the CI homepage or directly pull the latest version from GitHub. After that, you unzip the contents to the directory that's required. The final step is to edit the config.php to suit your needs and it's set up and ready for development.

There are also a lot of guides and tutorials from developers who have been using CI for a long time. This is because of the relative old age of the framework and the large community behind it.

CodeIgniter has a small footprint, just 3MB and that's including the user guide.

The documentation is clear, structured and thorough. It explains both commonly used and CodeIgniter specific concepts and always with clear examples.

Because it's relatively old and well-liked, it has an active community of developers behind it. It's used by a lot of websites in production.

The MIT License (MIT)

CodeIgniter is open source and is distributed under the MIT license.

CodeIgniter is tested by hundreds of thousand of developers that use it in production. This means that it's very hard for any bugs or problems to go unnoticed. Even when a new version is out, bugs are quickly found and patched up.

CodeIgniter has it's own templating engine built-in. It's based on a mustache-like templating language which is easy to learn for new developers who have never seen it. While experienced developers will feel very comfortable using it.

CodeIgniter lets you cache the web pages in order to decrease loading times and increase efficiency and performance.

CI4 will be out soon & is a rewrite..
"CodeIgniter 4 is a rewrite of the framework and is not backwards compatible."
So it will support ALOT more newer functionality built-in.

The thing that makes Silex stand out from other PHP microframeworks is the fact that it's built using some of Symfony2's components. Making it quite powerful but still lightweight enough to be considered a true microframework.

Silex is open source and is licensed under the MIT license.

Based on Pimple, Silex has a simple Dependency Injection container that consists of just one file and one class.

Silex makes use of Symfony2's HttpKernel which is used to abstract requests and responses. This in turn, makes it very easy to test apps created with the framework.

By using Pimple, the Silex application extends the Pimple class, which in turn is nothing more than an implementation of the ArrayAccess interface that has been a part of PHP since version 5.0.

This makes it possible to use an instance of the Application class as if it were an array. Like so:

$app = new Silex\Application();

$app['config'] = new Config($config_path);

This gives developers a great deal of flexibility when injecting dependencies and when testing.