CodeIgniter4 can be installed manually, or using Composer.

Manual Installation

CodeIgniter is installed in four steps:

  1. Unzip the package.
  2. Upload the CodeIgniter folders and files to your server. The index.php file will be in the public folder inside your project root.
  3. Open the application/Config/App.php file with a text editor and set your base URL. If you intend to use encryption or sessions, set your encryption key.
  4. If you intend to use a database, open the application/Config/Database.php file with a text editor and set your database settings.

For the best security, both the system and any application directories come placed above the web root so that they are not directly accessible via a browser. By default, .htaccess files are included in each directory to help prevent direct access, but it is best to remove them from public access entirely in case the web server configuration changes or doesn’t abide by the .htaccess.

If you would like to keep your views public it is also possible to move the views directory out of your application directory, to a corresponding folder inside public. If you do this, remember to open your main index.php file and set the $system_path, $application_folder and $view_folder variables, preferably with a full path, e.g. ‘/www/MyUser/system’.

One additional measure to take in production environments is to disable PHP error reporting and any other development-only functionality. In CodeIgniter, this can be done by setting the ENVIRONMENT constant, which is more fully described on the environments page. By default, the application will run using the “production” environment. To take advantage of the debugging tools provided, you should set the environment to “develop”.

That’s it!

If you’re new to CodeIgniter, please read the Getting Started section of the User Guide to begin learning how to build dynamic PHP applications. Enjoy!

Composer Installation