diff --git a/src/App.php b/src/App.php
index 760e7cb..2413d1c 100644
--- a/src/App.php
+++ b/src/App.php
@@ -85,6 +85,17 @@ class App {
     return !is_null(self :: $root_directory_path);
   }
 
+  /**
+   * Check if a specific configuration variable is set
+   *
+   * @param string $key The configuration variable key
+   * @param array|null $config Optional configuration to use instead of current loaded configuration
+   * @return bool
+   **/
+  public static function isset($key, &$config=null) {
+    return Config::isset($key, self :: $options) || (Config::loaded() && Config::isset($key));
+  }
+
   /**
    * Get a specific option value
    *
@@ -108,6 +119,19 @@ class App {
     );
   }
 
+  /**
+   * Set a specific option value
+   *
+   * @param string $key The configuration variable key
+   * @param mixed $value The configuration variable value
+   * @return boolean
+   **/
+  public static function set($key, $value) {
+    if (Config::isset($key, self :: $options))
+      return Config::set($key, $value, self :: $options);
+    return Config::set($key, $value);
+  }
+
   /**
    * Retreive application root directory path
    * @return string|null
diff --git a/src/Config.php b/src/Config.php
index 4e7efbc..886eb7b 100644
--- a/src/Config.php
+++ b/src/Config.php
@@ -101,6 +101,31 @@ Class Config {
     self :: $extra_variables[$key] = $value;
   }
 
+  /**
+   * Check if a specific configuration variable is set
+   *
+   * @param string $key The configuration variable key
+   * @param array|null $config Optional configuration to use instead of current loaded configuration
+   * @return bool
+   **/
+  public static function isset($key, &$config=null) {
+    if (array_key_exists($key, self :: $extra_variables))
+      return true;
+    if (!is_array($config) && !self :: loaded()) {
+      Log :: fatal('Configuration not loaded (on checking if %s is set)', $key);
+      exit(1);
+    }
+    $exploded_key = explode('.', $key);
+    if (!is_array($exploded_key)) return false;
+    $value = is_array($config)?$config:self :: $config;
+    foreach ($exploded_key as $k) {
+      if (!is_array($value) || !isset($value[$k]))
+        return false;
+      $value = $value[$k];
+    }
+    return true;
+  }
+
   /**
    * Get a specific configuration variable value
    *