diff --git a/src/App.php b/src/App.php
index c46cceb..7a89a6c 100644
--- a/src/App.php
+++ b/src/App.php
@@ -39,13 +39,30 @@ class App {
       exit(1);
     }
 
+    // Set config default values
+    App :: set_defaults(
+      array(
+        'overwrite_config_files' => array(),
+        'upload_tmp_directory' => null,
+        'upload_max_filesize' => null,
+        'sentry.enabled' => true,
+        'log.enabled' => true,
+        'session.enabled' => true,
+        'templates.enabled' => true,
+        'url.enabled' => true,
+        'mail.enabled' => true,
+        'i18n.enabled' => true,
+        'cli.enabled' => true,
+      )
+    );
+
     // Load overwrite configuration file
-    foreach (self :: get('overwrite_config_files', array(), 'array') as $file) {
+    foreach (self :: get('overwrite_config_files', null, 'array') as $file) {
       $file = Config::replace_variables($file);
       if (is_file($file)) Config::load($file, true);
     }
 
-    if (self :: get('sentry.enabled', true, 'bool'))
+    if (self :: get('sentry.enabled', null, 'bool'))
       SentryIntegration :: init();
     $sentry_transaction = new SentryTransaction();
     $sentry_span = new SentrySpan('app.init', 'Application initialization');
@@ -60,13 +77,13 @@ class App {
       Config :: ini_set('post_max_size', strval(self::get('upload_max_filesize', null, 'int') * 1.1));
     }
 
-    if (self :: get('log.enabled', true, 'bool'))
+    if (self :: get('log.enabled', null, 'bool'))
       Log::init();
-    if (self :: get('session.enabled', true, 'bool'))
+    if (self :: get('session.enabled', null, 'bool'))
       Session::init();
-    if (self :: get('templates.enabled', true, 'bool'))
+    if (self :: get('templates.enabled', null, 'bool'))
       Tpl :: init();
-    if (self :: get('url.enabled', true, 'bool')) {
+    if (self :: get('url.enabled', null, 'bool')) {
       Url::init();
       Url :: add_url_handler(null, array('EesyPHP\\App', 'handle_homepage'));
     }
@@ -74,11 +91,11 @@ class App {
       Auth :: init();
       Url :: add_url_handler('#^logout$#', array('EesyPHP\\App', 'handle_logout'), null, false);
     }
-    if (self :: get('mail.enabled', true, 'bool'))
+    if (self :: get('mail.enabled', null, 'bool'))
       Email :: init();
-    if (self :: get('i18n.enabled', true, 'bool'))
+    if (self :: get('i18n.enabled', null, 'bool'))
       I18n::init();
-    if (self :: get('cli.enabled', true, 'bool'))
+    if (self :: get('cli.enabled', null, 'bool'))
       Cli::init();
     $sentry_span->finish();
   }
@@ -175,6 +192,32 @@ class App {
     return Config::set($key, $value);
   }
 
+  /**
+   * Set a specific option default value
+   *
+   * @param string $key The configuration variable key
+   * @param mixed $value The configuration variable default value
+   * @return boolean
+   **/
+  public static function set_default($key, $value) {
+    return Config::set("default.$key", $value, self :: $options);
+  }
+
+  /**
+   * Set a specific options default value
+   *
+   * @param array<string,mixed> $values Associative array of configuration variables name and
+   *                                    default values
+   * @return boolean
+   **/
+  public static function set_defaults($values) {
+    $error = false;
+    foreach($values as $key => $value)
+      if (!self :: set_default($key, $value))
+        $error = true;
+    return !$error;
+  }
+
   /**
    * Retreive application root directory path
    * @return string|null
diff --git a/src/Auth.php b/src/Auth.php
index 96553e8..7d18384 100644
--- a/src/Auth.php
+++ b/src/Auth.php
@@ -36,7 +36,17 @@ class Auth {
    * @return void
    */
   public static function init() {
-    if (!self :: enabled()) return;
+    // Set config default values
+    App :: set_default(
+      'auth',
+      array(
+        'methods' => array(),
+        'backends' => array(),
+        'enabled' => self :: enabled(),
+        'allow_multiple_match' => null,
+        'allow_multiple_match_with_valid_password' => null,
+      )
+    );
     self :: $methods = array();
     foreach(App::get('auth.methods', array(), 'array') as $method) {
       if (!$method || !is_string($method)) {
diff --git a/src/Auth/Cas.php b/src/Auth/Cas.php
index cc52c8c..5594b76 100644
--- a/src/Auth/Cas.php
+++ b/src/Auth/Cas.php
@@ -25,6 +25,20 @@ class Cas extends Method {
     // In phpstan context, do not initialize
     if (defined('__PHPSTAN_RUNNING__') && constant('__PHPSTAN_RUNNING__'))
       return true;
+    // Set config default values
+    App :: set_default(
+      'auth.cas',
+      array(
+        'host' => null,
+        'port' => 443,
+        'context' => '/idp/cas',
+        'version' => '2.0',
+        'logout' => true,
+        'fake_authenticated_user' => null,
+        'debug_log_file' => null,
+        'ca_cert_certificate_path' => null,
+      )
+    );
     self :: $fake_authenticated_user = App :: get(
       'auth.cas.fake_authenticated_user', null, 'string');
     if (self :: $fake_authenticated_user) return true;
@@ -37,7 +51,7 @@ class Cas extends Method {
         return false;
     }
 
-    $cas_version = App :: get('auth.cas.version', '2.0', 'string');
+    $cas_version = App :: get('auth.cas.version', null, 'string');
     $supported_cas_versions = phpCAS::getSupportedProtocols();
     if (!array_key_exists($cas_version, $supported_cas_versions)) {
         Log :: error(
@@ -51,8 +65,8 @@ class Cas extends Method {
     phpCAS::client(
         $cas_version,
         App :: get('auth.cas.host'),
-        App :: get('auth.cas.port', 443, 'int'),
-        App :: get('auth.cas.context', '/idp/cas', 'string'),
+        App :: get('auth.cas.port', null, 'int'),
+        App :: get('auth.cas.context', null, 'string'),
         Url :: get_absolute_url("/")
     );
     if (App :: get('auth.cas.ca_cert_certificate_path'))
@@ -109,7 +123,7 @@ class Cas extends Method {
    * @return void
    */
   public static function logout() {
-    if (App :: get('auth.cas.logout', true, 'bool') && !self :: $fake_authenticated_user) {
+    if (App :: get('auth.cas.logout', null, 'bool') && !self :: $fake_authenticated_user) {
       if (App :: get('auth.cas.logout_url')) {
         Url :: redirect(App :: get('auth.cas.logout_url'));
         exit();
diff --git a/src/Auth/Db.php b/src/Auth/Db.php
index 149fd68..101413b 100644
--- a/src/Auth/Db.php
+++ b/src/Auth/Db.php
@@ -69,14 +69,28 @@ class Db extends Backend {
    * @return boolean
    */
   public static function init() {
+    // Set config default values
+    App :: set_default(
+      'auth.db',
+      array(
+        'dsn' => null,
+        'user' => null,
+        'password' => null,
+        'options' => array(),
+        'users_table' => 'users',
+        'username_field' => 'username',
+        'password_field' => 'password',
+        'exposed_fields' => array('name', 'mail'),
+      )
+    );
     self :: $dsn = App::get('auth.db.dsn', null, 'string');
     self :: $user = App::get('auth.db.user', null, 'string');
     self :: $password = App::get('auth.db.password', null, 'string');
-    self :: $options = App::get('auth.db.options', array(), 'array');
-    self :: $users_table = App::get('auth.db.users_table', 'users', 'string');
-    self :: $username_field = App::get('auth.db.username_field', 'username', 'string');
-    self :: $password_field = App::get('auth.db.password_field', 'password', 'string');
-    self :: $exposed_fields = App::get('auth.db.exposed_fields', array('name', 'mail'), 'array');
+    self :: $options = App::get('auth.db.options', null, 'array');
+    self :: $users_table = App::get('auth.db.users_table', null, 'string');
+    self :: $username_field = App::get('auth.db.username_field', null, 'string');
+    self :: $password_field = App::get('auth.db.password_field', null, 'string');
+    self :: $exposed_fields = App::get('auth.db.exposed_fields', null, 'array');
     return boolval(self :: $dsn);
   }
 
diff --git a/src/Auth/Form.php b/src/Auth/Form.php
index 97742a7..fb9b09d 100644
--- a/src/Auth/Form.php
+++ b/src/Auth/Form.php
@@ -16,6 +16,13 @@ class Form extends Method {
    * @return boolean
    */
   public static function init() {
+    // Set config default values
+    App :: set_default(
+      'auth.login_form',
+      array(
+        'display_other_methods' => array(),
+      )
+    );
     Url :: add_url_handler('#^login$#', array('EesyPHP\\Auth\\Form', 'handle_login'), null, false);
     Hook :: register('logged_in', array('\\EesyPHP\\Auth\\Form', 'logged_in_hook'));
     return true;
diff --git a/src/Auth/Http.php b/src/Auth/Http.php
index b0d3808..425a8eb 100644
--- a/src/Auth/Http.php
+++ b/src/Auth/Http.php
@@ -29,9 +29,18 @@ class Http extends Method {
    * @return boolean
    */
   public static function init() {
-    self :: $method = App::get('auth.http.method', 'PHP_AUTH', 'string');
+    // Set default config values
+    App :: set_default(
+      'auth.http',
+      array(
+        'method' => 'PHP_AUTH',
+        'realm' => _('Authentication required'),
+        'trust_without_password_challenge' => false,
+      )
+    );
+    self :: $method = App::get('auth.http.method', null, 'string');
     self :: $realm = App::get(
-      'auth.http.realm', _('Authentication required'), 'string');
+      'auth.http.realm', null, 'string');
     return true;
   }
 
@@ -91,7 +100,7 @@ class Http extends Method {
       return null;
     }
 
-    if (App :: get('auth.http.trust_without_password_challenge', false, 'bool'))
+    if (App :: get('auth.http.trust_without_password_challenge', null, 'bool'))
       $user = Auth :: get_user($auth_data['username']);
     else
       $user = Auth :: authenticate($auth_data['username'], $auth_data['password']);
diff --git a/src/Auth/Ldap.php b/src/Auth/Ldap.php
index 562ae5a..bb9d1fe 100644
--- a/src/Auth/Ldap.php
+++ b/src/Auth/Ldap.php
@@ -28,38 +28,49 @@ class Ldap extends Backend {
    */
   private static $connection = null;
 
-  /**
-   * Default LDAP user attributes configuration
-   * @var array<string,array>
-   */
-  private static $default_user_attributes = array(
-    'login' => array(
-      'ldap_name' => 'uid',
-      'type' => 'string',
-      'multivalued' => false,
-      'default' => null,
-    ),
-    'mail' => array(
-      'type' => 'string',
-      'multivalued' => false,
-      'default' => null,
-    ),
-    'name' => array(
-      'ldap_name' => 'displayName',
-      'alt_ldap_name' => 'cn',
-      'type' => 'string',
-      'multivalued' => false,
-      'default' => null,
-    ),
-  );
-
   /**
    * Initialize
    * @return bool
    */
   public static function init() {
+    // Set default config values
+    App :: set_default(
+      'auth.ldap',
+      array(
+        'host' => array(),
+        'port' => null,
+        'basedn' => null,
+        'binddn' => null,
+        'bindpw' => null,
+        'starttls' => false,
+        'user_filter_by_uid' => 'uid=[username]',
+        'user_basedn' => null,
+        'bind_with_username' => false,
+        'user_attributes' => array(
+          'login' => array(
+            'ldap_name' => 'uid',
+            'type' => 'string',
+            'multivalued' => false,
+            'default' => null,
+          ),
+          'mail' => array(
+            'type' => 'string',
+            'multivalued' => false,
+            'default' => null,
+          ),
+          'name' => array(
+            'ldap_name' => 'displayName',
+            'alt_ldap_name' => 'cn',
+            'type' => 'string',
+            'multivalued' => false,
+            'default' => null,
+          ),
+        ),
+        'netldap2_path' => 'Net/LDAP2.php',
+      )
+    );
     if (!class_exists('Net_LDAP2')) {
-      $path = App::get('auth.ldap.netldap2_path', 'Net/LDAP2.php', 'string');
+      $path = App::get('auth.ldap.netldap2_path', null, 'string');
       if (!@include($path)) {
         Log::error('Fail to load Net_LDAP2 (%s)', $path);
         return false;
@@ -73,11 +84,11 @@ class Ldap extends Backend {
     }
 
     self :: $ldap_config = array (
-      'host'  => implode(' ', App :: get('auth.ldap.host', array(), 'array')),
+      'host'  => implode(' ', App :: get('auth.ldap.host', null, 'array')),
       'basedn' => App :: get('auth.ldap.basedn', null, 'string'),
       'binddn' => App :: get('auth.ldap.bind_dn', null, 'string'),
       'bindpw' => App :: get('auth.ldap.bind_password', null, 'string'),
-      'starttls' => App :: get('starttls', false, 'bool'),
+      'starttls' => App :: get('starttls', null, 'bool'),
     );
     if ($port = App :: get('auth.ldap.port', null, 'int'))
       self :: $ldap_config['port'] = $port;
@@ -202,7 +213,7 @@ class Ldap extends Backend {
    * @return \EesyPHP\Auth\User|null|false The user object if found, null it not, false in case of error
    */
   public static function get_user($username) {
-    $attrs = App::get('auth.ldap.user_attributes', self :: $default_user_attributes, 'array');
+    $attrs = App::get('auth.ldap.user_attributes', null, 'array');
     $attrs_names = array();
     foreach($attrs as $attr => $attr_config) {
       $name = Config::get("ldap_name", $attr, 'string', false, $attr_config);
@@ -215,7 +226,7 @@ class Ldap extends Backend {
     $users = self :: search(
       str_replace(
         '[username]', Net_LDAP2_Filter::escape($username),
-        App::get('auth.ldap.user_filter_by_uid', 'uid=[username]', 'string')
+        App::get('auth.ldap.user_filter_by_uid', null, 'string')
       ),
       $attrs_names,
       App::get('auth.ldap.user_basedn', null, 'string')
@@ -261,7 +272,7 @@ class Ldap extends Backend {
   public static function check_password($user, $password) {
     $config = self :: $ldap_config;
     $config['binddn'] = (
-      App::get('auth.ldap.bind_with_username', false, 'bool')?
+      App::get('auth.ldap.bind_with_username', null, 'bool')?
       $user->username:
       $user->dn
     );
diff --git a/src/Email.php b/src/Email.php
index 3082b93..dd47bb9 100644
--- a/src/Email.php
+++ b/src/Email.php
@@ -10,90 +10,45 @@ use finfo;
 
 class Email {
 
-  /**
-   * Default sender
-   * @var string|null;
-   */
-  protected static $sender = null;
-
-  /**
-   * Sending method :
-   *  - mail : use PHP mail function
-   *  - sendmail : use sendmail system command
-   *  - smtp : use an SMTP server (PHP PEAR Net_SMTP required)
-   * @var string
-   */
-  protected static $send_method = 'mail';
-
-  /**
-   * Sending parameters
-   * @see http://pear.php.net/manual/en/package.mail.mail.factory.php
-   * @var array|null
-   */
-  protected static $send_params = null;
-
-  /**
-   * Catch all sent email recipient
-   * @var string|array<string>|null
-   */
-  protected static $catch_all = null;
-
-  /**
-   * Default headers to add on all sent emails
-   * @var array<string>
-   */
-  protected static $headers = array();
-
-  /**
-   * PHP PEAR Mail lib path
-   * @var string
-   */
-  protected static $php_mail_path = 'Mail.php';
-
-  /**
-   * PHP PEAR Mail lib path
-   * @var string
-   */
-  protected static $php_mail_mime_path = 'Mail/mime.php';
-
-
   /**
    * Initialization
-   * @param string|null $php_mail_path PHP PEAR Mail lib path (optional, default: from
-   *                    email.php_mail_path config key if set, 'Mail.php' otherwise)
-   * @param string|null $php_mail_mime_path PHP PEAR Mail lib path (optional, default: from
-   *                    email.php_mail_mime_path config key if set, 'Mail/mime.php' otherwise)
    * @return void
    */
-  public static function init($sender=null, $send_method=null, $send_params=null, $catch_all=null,
-                              $headers=null, $php_mail_path=null, $php_mail_mime_path=null) {
-    if (is_null($sender))
-      $sender = App::get('email.sender', null, 'string');
-    if ($sender) self :: $sender = $sender;
+  public static function init() {
+    // Set config default values
+    App :: set_default(
+      'email',
+      array(
+        // Default sender
+        'sender' => null,
 
-    if (is_null($send_method))
-      $send_method = App::get('email.send_method', null, 'string');
-    if ($send_method) self :: $send_method = $send_method;
+        /**
+         * Sending method :
+         *  - mail : use PHP mail function
+         *  - sendmail : use sendmail system command
+         *  - smtp : use an SMTP server (PHP PEAR Net_SMTP required)
+         */
+        'send_method' => null,
 
-    if (is_null($send_params))
-      $send_params = App::get('email.send_params', null, 'array');
-    if ($send_params) self :: $send_params = $send_params;
+        /**
+         * Sending parameters
+         * @see http://pear.php.net/manual/en/package.mail.mail.factory.php
+         */
+        'send_params' => array(),
 
-    if (is_null($catch_all))
-      $catch_all = App::get('email.catch_all');
-    if ($catch_all) self :: $catch_all = $catch_all;
+        // Catch all sent email recipient
+        'catch_all' => null,
 
-    if (is_null($headers))
-      $headers = App::get('email.headers', null, 'array');
-    if ($headers) self :: $headers = $headers;
+        // Default headers to add on all sent emails
+        'headers' => array(),
 
-    if (is_null($php_mail_path))
-      $php_mail_path = App::get('email.php_mail_path', null, 'string');
-    if ($php_mail_path) self :: $php_mail_path = $php_mail_path;
+        // PHP PEAR Mail lib path
+        'php_mail_path' => 'Mail.php',
 
-    if (is_null($php_mail_mime_path))
-      $php_mail_mime_path = App::get('email.php_mail_mime_path', null, 'string');
-    if ($php_mail_mime_path) self :: $php_mail_mime_path = $php_mail_mime_path;
+        // PHP PEAR Mail_mime lib path
+        'php_mail_mime_path' => 'Mail/mime.php',
+      )
+    );
   }
 
 
@@ -116,24 +71,29 @@ class Email {
   public static function send($from, $to, $subject, $msg, $html=false, $attachments=null,
                                    $headers=null, $encoding=null, $eol=null) {
     if (!class_exists('Mail'))
-      require_once(self :: $php_mail_path);
+      require_once(App :: get('php_mail_path', null, 'string'));
     if (!class_exists('Mail_mime'))
-      require_once(self :: $php_mail_mime_path);
+      require_once(App :: get('php_mail_mime_path', null, 'string'));
 
-    $mail_obj = Mail::factory(self :: $send_method, self :: $send_params);
+    $mail_obj = Mail::factory(
+      App :: get('email.send_method', null, 'string'),
+      App :: get('email.send_params', null, 'array')
+    );
 
     if (!$headers) $headers = array();
-    $headers = array_merge($headers, self :: $headers);
+    $headers = array_merge($headers, App :: get('email.headers', null, 'array'));
 
     Log :: trace(
       'Mail catch all: %s',
-        self :: $catch_all?
-        vardump(self :: $catch_all):'not set'
+        App :: get('email.catch_all')?
+        vardump(App :: get('email.catch_all')):'not set'
     );
-    if (self :: $catch_all) {
+    if (App :: get('email.catch_all')) {
       Log :: debug(
         'Mail catch to %s',
-        is_array(self :: $catch_all)?implode(',', self :: $catch_all):self :: $catch_all
+        is_array(App :: get('email.catch_all'))?
+        implode(',', App :: get('email.catch_all')):
+        App :: get('email.catch_all')
       );
       $msg .= sprintf(
         (
@@ -144,8 +104,9 @@ class Email {
         (is_array($to)?implode(',', $to):$to));
       $headers["X-Orig-To"] = $to;
       $to = (
-        is_array(self :: $catch_all)?
-        implode(',', self :: $catch_all):self :: $catch_all
+        is_array(App :: get('email.catch_all'))?
+        implode(',', App :: get('email.catch_all')):
+        App :: get('email.catch_all')
       );
     }
 
@@ -159,7 +120,7 @@ class Email {
       unset($headers['From']);
     }
     elseif (!$from) {
-      $from = self :: $sender;
+      $from = App::get('email.sender');
     }
 
     $headers["To"] = $to;
@@ -170,7 +131,7 @@ class Email {
 
     foreach(array_keys($headers) as $header) {
       if(in_array(strtoupper($header), array('BCC', 'CC'))) {
-        if (self :: $catch_all) {
+        if (App :: get('email.catch_all')) {
           Log :: debug("Mail catched: remove $header header");
           $msg .= sprintf(
             (
diff --git a/src/I18n.php b/src/I18n.php
index bb6dd30..1d6e547 100644
--- a/src/I18n.php
+++ b/src/I18n.php
@@ -35,25 +35,21 @@ class I18n {
    * Detect best translation language and configure the translation
    * system.
    *
-   * @param string|null $root_path The root directory path of translation files
-   *                    (optional, default: from i18n.root_directory config key if set,
-   *                    '${root_directory_path}/locales' otherwise)
-   * @param string|null $default_locale The default locale
-   *                    (optional, default: from i18n.default_locale config key if set,
-   *                    'en_US.UTF8' otherwise)
    * @return void
    */
-  public static function init($root_path=null, $default_locale=null) {
-    if (is_null($root_path))
-      self :: $root_path = App::get(
-        'i18n.root_directory', '${root_directory_path}/locales', 'string');
-    if (!is_null($root_path))
-      self :: $root_path = $root_path;
+  public static function init() {
+    // Set config default values
+    App :: set_default(
+      'i18n',
+      array(
+        'root_directory' => '${root_directory_path}/locales',
+        'default_locale' => null,
+      )
+    );
 
-    if (is_null($default_locale))
-      $default_locale = App::get('i18n.default_locale', null, 'string');
-    if (!is_null($default_locale))
-      self :: $default_locale = $default_locale;
+    self :: $root_path = App::get(
+      'i18n.root_directory', null, 'string');
+    $default_locale = App::get('i18n.default_locale', null, 'string');
 
     if (!class_exists('Locale')) {
       Log :: error('Locale PHP class does not exist. May be php-intl is not installed?');
diff --git a/src/Log.php b/src/Log.php
index a877459..804ae8d 100644
--- a/src/Log.php
+++ b/src/Log.php
@@ -38,12 +38,6 @@ class Log {
     'FATAL' => 5,
   );
 
-  /*
-   * Default log level
-   * @var string
-   */
-  protected static $default_level = 'WARNING';
-
   /*
    * Current log level
    * @var string|null
@@ -63,42 +57,46 @@ class Log {
 
   /**
    * Initialization
-   * @param string $filepath The log file path
-   *              (optional, default: from log.file_path or log.cli_file_path is set)
-   * @param string|null $level The log level
-   *              (optional, default: from log.level config key if set, otherwise,
-   *              see self :: $default_level)
-   * @param int|null $php_errors_levels PHP errors level as expected by set_error_handler()
-   *                 (optional, default: from log.php_errors_levels if set, E_ALL & ~E_STRICT
-   *                 if level is TRACE or DEBUG, and E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED
-   *                 otherwise)
    * @return void
    */
-  public static function init($filepath=null, $level=null, $php_errors_levels=null) {
-    if ($filepath)
-      self :: $filepath = $filepath;
-    elseif (php_sapi_name() == 'cli')
-      self :: $filepath = App::get(
-        'log.cli_logfile_path', App::get('log.cli_file_path'));
-    else
-      self :: $filepath = App::get('log.file_path');
+  public static function init() {
+    // Set config default values
+    App :: set_default(
+      'log',
+      array(
+        'level' => 'WARNING',
+        'file_path' => null,
+        'cli_file_path' => '${log.file_path}',
+        'default_locale' => null,
+        'error_log_fallback' => true,
+        'php_errors_levels' => array(),  // Depend of effective log level, see below
+      )
+    );
+    self :: $filepath = App::get(
+      php_sapi_name() == 'cli'?'log.cli_logfile_path':'log.file_path'
+    );
 
     // PHP error_log() fallback
-    self :: $error_log_fallback = App::get('log.error_log_fallback', true, 'bool');
+    self :: $error_log_fallback = App::get('log.error_log_fallback', null, 'bool');
 
     // Set log level:
     // Note: in Phpstan context, force FATAL level
     if (defined('__PHPSTAN_RUNNING__') && constant('__PHPSTAN_RUNNING__'))
       self :: set_level('FATAL');
     else
-      self :: set_level($level?$level:App::get('log.level'));
+      self :: set_level(App::get('log.level', null, 'string'));
 
+    App :: set_default(
+      'log.php_errors_levels',
+      in_array(self :: $level, array('DEBUG', 'TRACE'))?
+      array('E_ALL', '~E_STRICT'):
+      array('E_ALL', '~E_STRICT', '~E_NOTICE', '~E_DEPRECATED')
+    );
 
     // Log PHP errors
-    if (!is_null($php_errors_levels)) {
-      self :: $php_errors_levels = $php_errors_levels;
-    }
-    elseif ($levels = App::get('log.php_errors_levels', array(), 'array')) {
+    $levels = App::get('log.php_errors_levels', array(), 'array');
+    if ($levels) {
+      self :: $php_errors_levels = E_ALL;
       $code = 'self :: $php_errors_levels = ';
       while($level = array_shift($levels)) {
         if (!is_string($level)) continue;
@@ -125,14 +123,8 @@ class Log {
       }
       $code .= ";";
       eval($code);
+      set_error_handler(array('EesyPHP\\Log', 'on_php_error'), self :: $php_errors_levels);
     }
-    elseif (in_array(self :: $level, array('DEBUG', 'TRACE'))) {
-      self :: $php_errors_levels = E_ALL & ~E_STRICT;
-    }
-    else  {
-      self :: $php_errors_levels = E_ALL & ~E_NOTICE & ~E_STRICT & ~E_DEPRECATED;
-    }
-    set_error_handler(array('EesyPHP\\Log', 'on_php_error'), self :: $php_errors_levels);
 
     // Log uncatched exceptions
     set_exception_handler(array('EesyPHP\\Log', 'exception'));
@@ -162,7 +154,13 @@ class Log {
   public static function log($level, $message, ...$extra_args) {
     global $argv;
 
-    if (!array_key_exists($level, self :: $levels)) $level = self :: $default_level;
+    if (!array_key_exists($level, self :: $levels)) {
+      self :: warning(
+        "Invalid log level specified logging the message %s, use 'WARNING':\n%s",
+        $message, self :: get_debug_backtrace_context()
+      );
+      $level = 'WARNING';
+    }
     if (self :: $levels[$level] < self :: $levels[self :: $level]) return true;
     if(self :: $filepath && is_null(self :: $file_fd)) {
       self :: $file_fd = fopen(self :: $filepath, 'a');
@@ -337,13 +335,13 @@ class Log {
   public static function set_level($level=null) {
     // Set default log level (if not defined or invalid)
     if (is_null($level)) {
-      self :: $level = self :: $default_level;
+      self :: $level = App::get_default('log.level', null, 'string');
     }
     elseif (!array_key_exists($level, self :: $levels)) {
-      self :: $level = self :: $default_level;
+      self :: $level = App::get_default('log.level', null, 'string');
       self :: warning(
         "Invalid log level value found in configuration (%s). ".
-        "Set as default (%s).", vardump($level), self :: $default_level);
+        "Set as default (%s).", vardump($level), self :: $level);
     }
     else {
       self :: $level = $level;
diff --git a/src/SentryIntegration.php b/src/SentryIntegration.php
index 4afde2a..bf9024a 100644
--- a/src/SentryIntegration.php
+++ b/src/SentryIntegration.php
@@ -18,35 +18,31 @@ class SentryIntegration {
    * @see https://www.php.net/manual/fr/errorfunc.constants.php
    * @var array<int>
    */
-  protected static $php_error_types = array(
-    E_ERROR, E_PARSE, E_CORE_ERROR, E_COMPILE_ERROR, E_USER_ERROR,
-    E_RECOVERABLE_ERROR,E_DEPRECATED,
-  );
+  protected static $php_error_types;
 
   /**
    * Initialization
-   * @param string|null $dsn Sentry DSN
-   *                    (optional, default: from sentry.dsn config key if set, null otherwise)
-   * @param float|null $traces_sample_rate Sentry traces sample rate
-   *                   (optional, default: from sentry.traces_sample_rate config key if set,
-   *                   0.2 otherwise)
-   * @param array<int>|null $php_error_types Types of PHP error to log in Sentry
-   *                        (optional, default: from sentry.php_error_types config key if set,
-   *                        otherwise, see self::$php_error_types)
    * @return void
    */
-  public static function init($dsn=null, $traces_sample_rate=null,
-                              $php_error_types=null) {
+  public static function init() {
     // In phpstan context, do not initialize
     if (defined('__PHPSTAN_RUNNING__') && constant('__PHPSTAN_RUNNING__'))
       return;
-    \Sentry\init([
-        'dsn' => $dsn?$dsn:App::get('sentry.dsn'),
-        'traces_sample_rate' => (
-            $traces_sample_rate?
-            $traces_sample_rate:
-            App::get('sentry.traces_sample_rate', 0.2, 'float')
+    // Set config default values
+    App :: set_default(
+      'sentry',
+      array(
+        'dsn' => null,
+        'traces_sample_rate' => 0.2,
+        'php_error_types' => array(
+          'E_ERROR', 'E_PARSE', 'E_CORE_ERROR', 'E_COMPILE_ERROR', 'E_USER_ERROR',
+          'E_RECOVERABLE_ERROR', 'E_DEPRECATED',
         ),
+      )
+    );
+    \Sentry\init([
+        'dsn' => App::get('sentry.dsn'),
+        'traces_sample_rate' => App::get('sentry.traces_sample_rate', null, 'float'),
     ]);
 
     \Sentry\configureScope(function (\Sentry\State\Scope $scope): void {
@@ -56,12 +52,8 @@ class SentryIntegration {
         ]);
     });
 
-    if (!is_array($php_error_types))
-      $php_error_types = App::get(
-        'sentry.php_error_types', self :: $php_error_types, 'array'
-      );
     self :: $php_error_types = array();
-    foreach($php_error_types as $php_error_type) {
+    foreach(App::get('sentry.php_error_types', null, 'array') as $php_error_type) {
       if (is_string($php_error_type) && defined($php_error_type))
         $php_error_type = constant($php_error_type);
       if (!is_int($php_error_type)) continue;
diff --git a/src/Session.php b/src/Session.php
index 22c0df7..fed7fcb 100644
--- a/src/Session.php
+++ b/src/Session.php
@@ -11,30 +11,30 @@ class Session {
    * Session max duration (in seconds, default: 12h)
    * @var int
    */
-  protected static $max_duration = 12 * 60 * 60;
+  protected static $max_duration;
 
   /**
    * Initialization
-   * @param int|null $max_duration Session max duration in second
-   *                 (optional, default: from session.max_duration config key if set, 12h otherwise)
-   * @param int|null $timeout Session inactivity timeout in second
-   *                 (optional, default: from session.timeout config key if set, no timeout otherwise)
    * @return void
    */
-  public static function init($max_duration=null, $timeout=null) {
+  public static function init() {
     // In CLI or Phpstan context, do not initialize
     if (
       php_sapi_name() == "cli"
       || (defined('__PHPSTAN_RUNNING__') && constant('__PHPSTAN_RUNNING__'))
     )
       return;
+    // Set config default values
+    App :: set_default(
+      'session',
+      array(
+        'max_duration' => 43200,  // 12h
+        'timeout' => null,
+      )
+    );
 
     // Define session max duration
-    if (is_null($max_duration))
-      $max_duration = App::get('session.max_duration', null, 'int');
-    if (is_int($max_duration))
-      self :: $max_duration = $max_duration;
-
+    self :: $max_duration = App::get('session.max_duration', null, 'int');
     Config :: ini_set('session.gc_maxlifetime', strval(self :: $max_duration));
     Config :: ini_set('session.cookie_lifetime', strval(self :: $max_duration));
 
@@ -47,9 +47,8 @@ class Session {
     }
 
     // Handle session timeout
-    if (is_null($timeout))
-      $timeout = App::get('session.timeout', null, 'int');
-    if (is_int($timeout) && $timeout) {
+    $timeout = App::get('session.timeout', null, 'int');
+    if ($timeout) {
       if (!isset($_SESSION['session_last_access'])) {
         Log :: debug('Set initial session last access');
         $_SESSION['session_last_access'] = time();
diff --git a/src/Tpl.php b/src/Tpl.php
index 8acb4be..2dd817f 100644
--- a/src/Tpl.php
+++ b/src/Tpl.php
@@ -33,12 +33,6 @@ class Tpl {
    */
   public static $templates_directories = array();
 
-  /**
-   * Smarty cache templates directory path
-   * @var string
-   */
-  public static $templates_c_dir;
-
   /**
    * Enable/disable AJAX returned data debugging in logs
    * @var bool
@@ -83,28 +77,38 @@ class Tpl {
 
   /**
    * Initialization
-   * @param string $templates_dir Smarty templates directory path
-   *               (optional, default: from templates.directory config key)
-   * @param string $templates_c_dir Smarty cache templates directory path
-   *               (optional, default: from templates.cache_directory config key)
-   * @param bool $debug_ajax Enable/disable AJAX returned data debugging in logs
-   *             (optional, default: from templates.debug_ajax or debug_ajax config keys if set,
-   *             false otherwise)
-   * @param bool $static_root_url Configure custom root URL path for static files
-   *             (optional, default: from templates.static_root_url config key if set,
-   *             '/static' otherwise. Set to False to disable)
    * @return void
    */
-  public static function init($templates_dir=null, $templates_c_dir=null, $debug_ajax=null,
-                              $static_root_url=null) {
+  public static function init() {
     // In phpstan context, do not initialize
     if (defined('__PHPSTAN_RUNNING__') && constant('__PHPSTAN_RUNNING__'))
       return;
+
+    // Set config default values
+    App :: set_default(
+      'templates',
+      array(
+        // Main Smarty templates directory path
+        'directory' => null,
+        // Smarty cache templates directory path
+        // Default: see below, compute only if not set
+        'cache_directory' => null,
+        'main_pagetitle' => null,
+        'static_root_url' => 'static/',
+        'static_directories' => array(),
+        'included_css_files' => array(),
+        'included_js_files' => array(),
+        'webstats_js_code' => null,
+        'upload_max_filesize' => null,
+        'debug_ajax' => App::get('debug_ajax', false, 'bool'),
+      )
+    );
+
     // Handle templates directories
     self :: $core_templates_directory = realpath(__DIR__."/../templates");
     self :: register_templates_directory(self :: $core_templates_directory);
-    if (is_null($templates_dir))
-      $templates_dir = App::get('templates.directory', null, 'string');
+
+    $templates_dir = App::get('templates.directory', null, 'string');
     if ($templates_dir) {
       if (!is_dir($templates_dir))
         Log :: fatal("Template directory not found (%s)", $templates_dir);
@@ -112,8 +116,7 @@ class Tpl {
     }
 
     // Handle and check templates_c directories
-    if (is_null($templates_c_dir))
-      $templates_c_dir = App::get('templates.cache_directory', null, 'string');
+    $templates_c_dir = App::get('templates.cache_directory', null, 'string');
     if ($templates_c_dir) {
       if (!is_dir($templates_c_dir) || !is_writable($templates_c_dir)) {
         Log :: fatal(
@@ -151,18 +154,17 @@ class Tpl {
           $templates_c_dir);
         return;
       }
+      App :: set_default('templates.cache_directory', $templates_c_dir);
     }
     self :: $smarty = new Smarty();
     self :: $smarty->setTemplateDir(self :: $core_templates_directory);
     self :: $smarty->setCompileDir($templates_c_dir);
     self :: $smarty->registerResource('Tpl', new TplSmartyResource());
-    if (is_null($debug_ajax))
-      $debug_ajax = App::get('templates.debug_ajax', App::get('debug_ajax'));
+    $debug_ajax = App::get('templates.debug_ajax', null, 'bool');
     self :: $_debug_ajax = boolval($debug_ajax);
     Log :: register_fatal_error_handler(array('\\EesyPHP\\Tpl', 'fatal_error'));
 
-    if (is_null($static_root_url))
-      $static_root_url = App::get('templates.static_root_url', 'static/', 'string');
+    $static_root_url = App::get('templates.static_root_url', null, 'string');
     if ($static_root_url) {
       if (substr($static_root_url, 0, 1) == '/')
         $static_root_url = substr($static_root_url, 1);
@@ -173,7 +175,7 @@ class Tpl {
       self :: register_static_directory(self :: $core_static_directory, 100);
       self :: register_function('static_url', array('EesyPHP\\Tpl', 'smarty_static_url'));
 
-      foreach(App :: get('templates.static_directories', array(), 'array') as $path)
+      foreach(App :: get('templates.static_directories', null, 'array') as $path)
         self :: register_static_directory($path);
 
       self :: register_function('var_dump', array('EesyPHP\\Tpl', 'smarty_var_dump'));
@@ -365,8 +367,8 @@ class Tpl {
     self :: assign('session_key', isset($_SESSION['session_key'])?$_SESSION['session_key']:null);
 
     // Handle CSS & JS files included
-    self :: add_css_file(App::get('templates.included_css_files', array(), 'array'));
-    self :: add_js_file(App::get('templates.included_js_files', array(), 'array'));
+    self :: add_css_file(App::get('templates.included_css_files', null, 'array'));
+    self :: add_js_file(App::get('templates.included_js_files', null, 'array'));
 
     // Messages
     self :: assign('errors', self :: get_errors());
diff --git a/src/Url.php b/src/Url.php
index 1e3e89f..8e5f993 100644
--- a/src/Url.php
+++ b/src/Url.php
@@ -58,22 +58,23 @@ class Url {
 
   /**
    * Initialization
-   * @param string|null $public_root_url The application public root URL
-   *                    (optional, default: from public_root_url config key)
-   * @param bool $api_mode Enable/disable API mode
    * @return void
    */
-  public static function init($public_root_url=null, $api_mode=false) {
+  public static function init() {
+    // Set default config values
+    App :: set_default('public_root_url', null);
+    App :: set_default('api_mode', false);
+
     if (php_sapi_name() == 'cli-server' && getenv('EESYPHP_SERVE_URL'))
       $public_root_url = getenv('EESYPHP_SERVE_URL');
-    else if (is_null($public_root_url))
+    else
       $public_root_url = App::get('public_root_url', null, 'string');
     if (is_string($public_root_url) && $public_root_url) {
       // Remove trailing slash
       $public_root_url = rtrim($public_root_url, '/');
       self :: $public_root_url = $public_root_url?$public_root_url:null;
     }
-    self :: $_api_mode = boolval($api_mode);
+    self :: $_api_mode = boolval(App::get('api_mode', null, 'bool'));
   }
 
   /**