CakePHP Folder Structure

After you've created a new application from the pieceofcake2/app skeleton (see Installation), these are the files and folders you should see:

• bin
• config
• logs
• plugins
• resources
• src
• templates
• tests
• tmp
• vendor
• webroot
• composer.json

You'll notice a few main folders:

• The src, config and templates folders will be where you work your magic: they're where your application's files will be placed.
• The vendor folder is managed by Composer. It contains CakePHP itself (vendor/pieceofcake2/cakephp) and any third-party PHP libraries you add with Composer. Make a personal commitment not to edit files in this folder. We can't help you if you've modified the core. Instead, look into modifying Application Extensions.
• The webroot folder is the document root of your application.

The Application Folders

Let's look a little closer at the folders of the application.

bin
Contains the cake console script, which runs the shells of CakePHP and of your application, for example bin/cake server or bin/cake test. For more information see Shells, Tasks & Console Tools.

config
Holds the (few) configuration files CakePHP uses. Database connection details, bootstrapping, core configuration files and more should be stored here. config/define.php defines the paths of the application folders.

logs
CakePHP writes its log files here. See Logging.

plugins
Contains plugin packages. Plugins installed with Composer are placed here.

resources/locales
Stores string files for internationalization.

src
Contains the PHP code of your application:

• src/Console/Command contains the console commands (shells) and, in Task/, the console tasks for your application. src/Console/Templates can contain templates to customize the output of bake.
• src/Controller contains your application's controllers and, in Component/, their components.
• src/Lib contains libraries that do not come from 3rd parties or external vendors. This allows you to separate your organization's internal libraries from vendor libraries.
• src/Model contains your application's models and, in Behavior/ and Datasource/, behaviors and datasources.
• src/View/Helper contains your application's helpers.

templates
Presentational files are placed here: view files in a folder per controller (for example templates/Posts/index.ctp), elements in Elements/, error pages in Errors/, layouts in Layouts/ and email templates in Emails/.

tests
This directory contains all the test cases and test fixtures for your application. The tests/TestCase directory should mirror your application and contain one or more test cases per class in your application. Fixtures are stored in tests/Fixture. For more information on test cases and test fixtures, refer to the Testing documentation.

tmp
This is where CakePHP stores temporary data. The actual data it stores depends on how you have CakePHP configured, but this folder is usually used to store model descriptions, cached views, and sometimes session information.

Make sure that this folder exists and is writable, or the performance of your application will be severely impacted. In debug mode, CakePHP will warn you if the folder is absent or not writable.

vendor
Contains the packages installed by Composer, including CakePHP itself. Add third-party libraries with composer require and they are autoloaded through vendor/autoload.php. Don't edit or add files here by hand.

webroot
In a production setup, this folder should serve as the document root for your application. Folders here also serve as holding places for CSS stylesheets, images, and JavaScript files.

The Legacy app/ Layout

Applications created with older versions of CakePHP 2 keep all of their code in an app/ folder. CakePHP supports this layout as well, and detects which layout an application uses. The folders correspond as follows:

Legacy (app/)	Modern
app/Config	config/
app/Console	src/Console/
app/Console/cake	bin/cake
app/Controller	src/Controller/
app/Lib	src/Lib/
app/Locale	resources/locales/
app/Model	src/Model/
app/Plugin	plugins/
app/Test/Case, app/Test/Fixture	tests/TestCase/, tests/Fixture/
app/tmp	tmp/
app/tmp/logs	logs/
app/Vendor	vendor/ (managed by Composer)
app/View (.ctp files)	templates/
app/View/Helper	src/View/Helper/
app/webroot	webroot/

Moving to the Modern Layout

You can move a legacy application to the modern layout gradually, while it keeps running on CakePHP 2:

1. Copy config/define.php, bin/cake, webroot/index.php and webroot/test.php from the pieceofcake2/app skeleton. config/define.php sets APP_DIR to src.
2. Move your files according to the table above, for example configuration files first, then the PHP code in src/, then the templates, and finally the tests. The code itself, including App::uses() calls, does not need to change. Tests can stay in app/Test/ for a while, because the test suite finds tests in both Test/Case/ and tests/TestCase/.
3. Install plugins and third-party libraries with Composer instead of keeping them in app/Plugin/ and app/Vendor/.
4. Optionally, add "classmap": ["src/"] to the autoload section of composer.json and run composer dump-autoload, so you can remove App::uses() calls for your own classes.

Because the modern layout matches the one used by CakePHP 5, moving to it first lets you separate the folder restructuring from a later upgrade of the code.