The yii2-markdown extension can be installed automatically or manually using one of these options:

$ php composer.phar require kartik-v/yii2-markdown "dev-master"

"kartik-v/yii2-markdown": "dev-master"

You must setup the markdown module by registering it in the modules section of your Yii Configuration file. View a complete demo.

'modules' = [
    /* your other modules */
    'markdown' => [
        'class' => 'kartik\markdown\Module',
    ]
];

You can setup additional configuration options for the markdown module:

'modules' = [
    'markdown' => [
        // the module class
        'class' => 'kartik\markdown\Module',
        
        // the controller action route used for markdown editor preview
        'previewAction' => '/markdown/parse/preview',
        
        // the controller action route used for downloading the markdown exported file
        'downloadAction' => '/markdown/parse/download',
        
        // the list of custom conversion patterns for post processing
        'customConversion' => [
            '<table>' => '<table class="table table-bordered table-striped">'
        ],
        
        // whether to use PHP SmartyPantsTypographer to process Markdown output
        'smartyPants' => true,
        
        // array the the internalization configuration for this module
        'i18n' => [
            'class' => 'yii\i18n\PhpMessageSource',
            'basePath' => '@markdown/messages',
            'forceTranslation' => true
        ];        
    ]
];

use kartik\markdown\Markdown;
echo Markdown::convert($content);

1. Configurable toolbar and buttons for formatting content
2. Live preview of Markdown formatted text as HTML
3. Maximize editor for full screen editing
4. Implements PHP Markdown Extra and PHP SmartyPantsTypographer functionality as provided by the MarkdownConverter.
5. Uses Bootstrap library styling wherever possible
6. Allows saving/exporting of the text-editor contents as Text or HTML
7. Configurable header, footer, and input options.
8. Supports localization and customization of messages and content.

// add this in your view
use kartik\markdown\MarkdownEditor;

// usage with Active Form 
echo $form->field($model, 'markdown')->widget(
    MarkdownEditor::classname(), 
    ['height' => 300, 'encodeLabels' => false]
);

// usage with model
echo MarkdownEditor::widget([
    'model' => $model, 
    'attribute' => 'markdown',
]);

// usage without model
echo MarkdownEditor::widget([
    'name' => 'markdown', 
    'value' => $value,
]);