diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3b337c2..757775a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@ dev
 - [ ] add module to check deprecated PHP function
 - [ ] add module to check directory structure
 - [ ] write documentation of php class
+- add module to use external php-cs-fixer
 
 0.3 - 2021.10.29
 - use of xmlTag to generate dcstore.xml contents
diff --git a/_admin.php b/_admin.php
index bd1497d..d789ea9 100644
--- a/_admin.php
+++ b/_admin.php
@@ -1,16 +1,15 @@
 <?php
 /**
  * @brief improve, a plugin for Dotclear 2
- * 
+ *
  * @package Dotclear
  * @subpackage Plugin
- * 
+ *
  * @author Jean-Christian Denis and contributors
- * 
+ *
  * @copyright Jean-Christian Denis
  * @copyright GPL-2.0 https://www.gnu.org/licenses/gpl-2.0.html
  */
-
 $core->blog->settings->addNamespace('improve');
 
 $core->addBehavior('adminDashboardFavorites', ['ImproveBehaviors', 'adminDashboardFavorites']);
@@ -22,6 +21,7 @@ $core->addBehavior('improveAddAction', ['ImproveActionGitshields', 'create']);
 $core->addBehavior('improveAddAction', ['ImproveActionLicensefile', 'create']);
 //$core->addBehavior('improveAddAction', ['ImproveActionLicense', 'create']);
 $core->addBehavior('improveAddAction', ['ImproveActionNewline', 'create']);
+$core->addBehavior('improveAddAction', ['ImproveActionPhpcsfixer', 'create']);
 $core->addBehavior('improveAddAction', ['ImproveActionPhpheader', 'create']);
 $core->addBehavior('improveAddAction', ['ImproveActionTab', 'create']);
 $core->addBehavior('improveAddAction', ['ImproveActionZip', 'create']);
@@ -49,4 +49,4 @@ class ImproveBehaviors
             ]
         );
     }
-}
\ No newline at end of file
+}
diff --git a/_prepend.php b/_prepend.php
index 6fb4e52..d30d2aa 100644
--- a/_prepend.php
+++ b/_prepend.php
@@ -1,23 +1,22 @@
 <?php
 /**
  * @brief improve, a plugin for Dotclear 2
- * 
+ *
  * @package Dotclear
  * @subpackage Plugin
- * 
+ *
  * @author Jean-Christian Denis and contributors
- * 
+ *
  * @copyright Jean-Christian Denis
  * @copyright GPL-2.0 https://www.gnu.org/licenses/gpl-2.0.html
  */
-
 if (!defined('DC_RC_PATH')) {
     return;
 }
 
 $improve_libs = [
-    'Improve'                   => 'class.improve.php',
-    'ImproveAction'             => 'class.improve.action.php',
+    'Improve'       => 'class.improve.php',
+    'ImproveAction' => 'class.improve.action.php',
 
     'ImproveActionDcdeprecated' => 'lib.improve.action.dcdeprecated.php',
     'ImproveActionDcstore'      => 'lib.improve.action.dcstore.php',
@@ -25,11 +24,12 @@ $improve_libs = [
     'ImproveActionGitshields'   => 'lib.improve.action.gitshields.php',
     'ImproveActionLicensefile'  => 'lib.improve.action.licensefile.php',
     'ImproveActionNewline'      => 'lib.improve.action.php',
+    'ImproveActionPhpcsfixer'   => 'lib.improve.action.phpcsfixer.php',
     'ImproveActionPhpheader'    => 'lib.improve.action.phpheader.php',
     'ImproveActionTab'          => 'lib.improve.action.php',
     'ImproveActionZip'          => 'lib.improve.action.zip.php',
     'ImproveZipFileZip'         => 'lib.improve.action.zip.php'
 ];
-foreach($improve_libs as $class => $file) {
+foreach ($improve_libs as $class => $file) {
     $__autoload[$class] = dirname(__FILE__) . '/inc/' . $file;
-}
\ No newline at end of file
+}
diff --git a/inc/dc.phpcsfixer.rules.php b/inc/dc.phpcsfixer.rules.php
new file mode 100644
index 0000000..6cc8a0b
--- /dev/null
+++ b/inc/dc.phpcsfixer.rules.php
@@ -0,0 +1,65 @@
+<?php
+
+// Adapted from https://gist.github.com/codfish/c77d348820c1c6b4ebe4a66dc2291c74
+
+/**
+ * Rules we follow are from PSR-2 as well as the rectified PSR-2 guide.
+ *
+ * - https://github.com/FriendsOfPHP/PHP-CS-Fixer
+ * - https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md
+ * - https://github.com/php-fig-rectified/fig-rectified-standards/blob/master/PSR-2-R-coding-style-guide-additions.md
+ *
+ * If something isn't addressed in either of those, some other common community rules are
+ * used that might not be addressed explicitly in PSR-2 in order to improve code quality
+ * (so that devs don't need to comment on them in Code Reviews).
+ *
+ * For instance: removing trailing white space, removing extra line breaks where
+ * they're not needed (back to back, beginning or end of function/class, etc.),
+ * adding trailing commas in the last line of an array, etc.
+ */
+$finder = PhpCsFixer\Finder::create()
+    ->exclude('node_modules')
+    ->exclude('vendor')
+    ->in(__DIR__);
+
+$config = new PhpCsFixer\Config();
+
+return $config
+    ->setRules([
+        '@PSR2'                  => true,
+        'array_indentation'      => true,
+        'array_syntax'           => ['syntax' => 'short'],
+        'binary_operator_spaces' => [
+            'default'   => 'align_single_space_minimal',
+            'operators' => [
+                '=>' => 'align_single_space_minimal',
+            ]
+        ],
+        'blank_line_before_statement'           => true,
+        'braces'                                => ['allow_single_line_closure' => true],
+        'cast_spaces'                           => true,
+        'combine_consecutive_unsets'            => true,
+        'concat_space'                          => ['spacing' => 'one'],
+        'linebreak_after_opening_tag'           => true,
+        'no_blank_lines_after_class_opening'    => true,
+        'no_blank_lines_after_phpdoc'           => true,
+        'no_break_comment'                      => false,
+        'no_extra_blank_lines'                  => true,
+        'no_trailing_comma_in_singleline_array' => true,
+        'no_whitespace_in_blank_line'           => true,
+        'no_spaces_around_offset'               => true,
+        'no_unused_imports'                     => true,
+        'no_useless_else'                       => true,
+        'no_useless_return'                     => true,
+        'no_whitespace_before_comma_in_array'   => true,
+        'normalize_index_brace'                 => true,
+        'phpdoc_indent'                         => true,
+        'phpdoc_to_comment'                     => true,
+        'phpdoc_trim'                           => true,
+        'return_type_declaration'               => ['space_before' => 'none'],
+        'single_quote'                          => true,
+        'ternary_to_null_coalescing'            => true,
+        'trailing_comma_in_multiline'           => false,
+        'trim_array_spaces'                     => true,
+    ])
+    ->setFinder($finder);
diff --git a/inc/lib.improve.action.phpcsfixer.php b/inc/lib.improve.action.phpcsfixer.php
new file mode 100644
index 0000000..9ba38e7
--- /dev/null
+++ b/inc/lib.improve.action.phpcsfixer.php
@@ -0,0 +1,110 @@
+<?php
+/**
+ * @brief improve, a plugin for Dotclear 2
+ *
+ * @package Dotclear
+ * @subpackage Plugin
+ *
+ * @author Jean-Christian Denis and contributors
+ *
+ * @copyright Jean-Christian Denis
+ * @copyright GPL-2.0 https://www.gnu.org/licenses/gpl-2.0.html
+ */
+class ImproveActionPhpcsfixer extends ImproveAction
+{
+    protected static $errors = [
+        0  => 'OK.',
+        1  => 'General error (or PHP minimal requirement not matched).',
+        4  => 'Some files have invalid syntax (only in dry-run mode).',
+        8  => 'Some files need fixing (only in dry-run mode).',
+        16 => 'Configuration error of the application.',
+        32 => 'Configuration error of a Fixer.',
+        64 => 'Exception raised within the application'
+    ];
+
+    protected function init(): bool
+    {
+        $this->setProperties([
+            'id'       => 'phpcsfixer',
+            'name'     => __('PHP CS Fixer'),
+            'desc'     => __('Fix PSR coding style using Php CS Fixer'),
+            'priority' => 920,
+            'config'   => true,
+            'types'    => ['plugin', 'theme']
+        ]);
+
+        return true;
+    }
+
+    public function isConfigured(): bool
+    {
+        return !empty($this->getSetting('phpcsf_path'));
+    }
+
+    public function configure($url): ?string
+    {
+        if (!empty($_POST['save'])) {
+            $this->setSettings([
+                'phpexe_path' => !empty($_POST['phpexe_path']) ? $_POST['phpexe_path'] : '',
+                'phpcsf_path' => !empty($_POST['phpcsf_path']) ? $_POST['phpcsf_path'] : ''
+            ]);
+            $this->redirect($url);
+        }
+
+        return
+        '<p class="info">' . sprintf(
+            __('You must have installed %s to use this tool'),
+            '<a href="https://github.com/FriendsOfPHP/PHP-CS-Fixer">php-cs-fixer</a>'
+        ) . '</p>' .
+        '<p><label class="classic" for="phpexe_path">' .
+        __('Root directory of PHP executable:') . '<br />' .
+        form::field('phpexe_path', 160, 255, $this->getSetting('phpexe_path')) . '</label>' .
+        '</p>' .
+        '<p class="form-note">' .
+            __('If this server is under unix, leave it empty.') . ' ' .
+            __('If this server is under Windows, put here directory to php executable (without executable file name).') .
+        ' C:\path_to\php</p>' .
+        '<p><label class="classic" for="phpcsf_path">' .
+        __('Root directory to "friendsofphp php-cs-fixer":') . '<br />' .
+        form::field('phpcsf_path', 160, 255, $this->getSetting('phpcsf_path')) . '</label>' .
+        '</p>' .
+        '<p class="form-note">' . __('Do not add file name to the end of path.') . ' \path_to\tools\php-cs-fixer\vendor\friendsofphp\php-cs-fixer</p>';
+    }
+
+    public function closeModule(): ?bool
+    {
+        $phpexe_path = path::real($this->getSetting('phpexe_path'));
+        if (!empty($phpexe_path)) {
+            $phpexe_path .= '/';
+        }
+        $phpcsf_path = path::real($this->getSetting('phpcsf_path'));
+
+        $command = sprintf(
+            '%sphp %s/php-cs-fixer fix %s --config=%s/dc.phpcsfixer.rules.php',
+            $phpexe_path,
+            $phpcsf_path,
+            $this->module['sroot'],
+            dirname(__FILE__)
+        );
+
+        try {
+            exec($command, $output, $error);
+            if (empty($output)) {
+                if (isset(self::$errors[$error])) {
+                    $this->setError(self::$errors[$error]);
+
+                    return false;
+                }
+
+                throw new Exception('oops');
+            }
+            $this->setSuccess(sprintf('<pre>%s</pre>', implode('<br />', $output)));
+
+            return true;
+        } catch (Exception $e) {
+            $this->setError(__('Failed to run php-cs-fixer'));
+
+            return false;
+        }
+    }
+}