diff --git a/system/src/Grav/Common/GPM/GPM.php b/system/src/Grav/Common/GPM/GPM.php
index ae48538c7..94a7eed14 100644
--- a/system/src/Grav/Common/GPM/GPM.php
+++ b/system/src/Grav/Common/GPM/GPM.php
@@ -3,48 +3,119 @@ namespace Grav\Common\GPM;
 
 use Grav\Common\Iterator;
 
-class GPM extends Iterator {
-    private $installed, $repository;
+class GPM extends Iterator
+{
+    /**
+     * Local installed Packages
+     * @var Packages
+     */
+    private $installed;
+
+    /**
+     * Remote available Packages
+     * @var Packages
+     */
+    private $repository;
+
+    /**
+     * Internal cache
+     * @var Iterator
+     */
     protected $cache;
 
-    public function __construct($refresh = false, $callback = null) {
+    /**
+     * Creates a new GPM instance with Local and Remote packages available
+     * @param boolean  $refresh  Applies to Remote Packages only and forces a refetch of data
+     * @param callable $callback Either a function or callback in array notation
+     */
+    public function __construct($refresh = false, $callback = null)
+    {
         $this->installed  = new Local\Packages();
         $this->repository = new Remote\Packages($refresh, $callback);
     }
 
-    public function getInstalled() {
+    /**
+     * Returns the Locally installed packages
+     * @return Iterator The installed packages
+     */
+    public function getInstalled()
+    {
         return $this->installed;
     }
 
-    public function countInstalled() {
+    /**
+     * Returns the amount of locally installed packages
+     * @return integer Amount of installed packages
+     */
+    public function countInstalled()
+    {
         return count($this->getInstalled());
     }
 
-    public function getInstalledPlugin($slug) {
+    /**
+     * Return the instance of a specific Plugin
+     * @param  string  $slug The slug of the Plugin
+     * @return Package The instance of the Plugin
+     */
+    public function getInstalledPlugin($slug)
+    {
         return $this->installed['plugins'][$slug];
     }
 
-    public function getInstalledPlugins() {
+    /**
+     * Returns the Locally installed plugins
+     * @return Iterator The installed plugins
+     */
+    public function getInstalledPlugins()
+    {
         return $this->installed['plugins'];
     }
 
-    public function isPluginInstalled($slug) {
+    /**
+     * Checks if a Plugin is installed
+     * @param  string  $slug The slug of the Plugin
+     * @return boolean True if the Plugin has been installed. False otherwise
+     */
+    public function isPluginInstalled($slug)
+    {
         return isset($this->installed['plugins'][$slug]);
     }
 
-    public function getInstalledTheme($slug) {
+    /**
+     * Return the instance of a specific Theme
+     * @param  string  $slug The slug of the Theme
+     * @return Package The instance of the Theme
+     */
+    public function getInstalledTheme($slug)
+    {
         return $this->installed['themes'][$slug];
     }
 
-    public function getInstalledThemes() {
+    /**
+     * Returns the Locally installed themes
+     * @return Iterator The installed themes
+     */
+    public function getInstalledThemes()
+    {
         return $this->installed['themes'];
     }
 
-    public function isThemeInstalled($slug) {
+    /**
+     * Checks if a Theme is installed
+     * @param  string  $slug The slug of the Theme
+     * @return boolean True if the Theme has been installed. False otherwise
+     */
+    public function isThemeInstalled($slug)
+    {
         return isset($this->installed['themes'][$slug]);
     }
 
-    public function countUpdates() {
+    /**
+     * Returns the amount of updates available
+     * @return integer Amount of available updates
+     */
+    public function countUpdates()
+    {
         $count = 0;
 
         $count += count($this->getUpdatablePlugins());
@@ -53,12 +124,19 @@ class GPM extends Iterator {
         return $count;
     }
 
-    public function getUpdatable() {
+    /**
+     * Returns an array of Plugins and Themes that can be updated.
+     * Plugins and Themes are extended with the `available` property that relies to the remote version
+     * @return array Array of updatable Plugins and Themes.
+     *               Format: ['total' => int, 'plugins' => array, 'themes' => array]
+     */
+    public function getUpdatable()
+    {
         $plugins = $this->getUpdatablePlugins();
         $themes  = $this->getUpdatableThemes();
 
         $items = [
-            'total'   => count($plugins) + count($themes),
+            'total'   => count($plugins)+count($themes),
             'plugins' => $plugins,
             'themes'  => $themes
         ];
@@ -66,7 +144,13 @@ class GPM extends Iterator {
         return $items;
     }
 
-    public function getUpdatablePlugins() {
+    /**
+     * Returns an array of Plugins that can be updated.
+     * The Plugins are extended with the `available` property that relies to the remote version
+     * @return Iterator Array of updatable Plugins
+     */
+    public function getUpdatablePlugins()
+    {
         $items      = [];
         $repository = $this->repository['plugins'];
 
@@ -91,14 +175,27 @@ class GPM extends Iterator {
         }
 
         $this->cache[__METHOD__] = $items;
+
         return $items;
     }
 
-    public function isPluginUpdatable($plugin) {
+    /**
+     * Checks if a Plugin is Updatable
+     * @param  string  $plugin The slug of the Plugin
+     * @return boolean True if the Plugin is updatable. False otherwise
+     */
+    public function isPluginUpdatable($plugin)
+    {
         return array_key_exists($plugin, $this->getUpdatablePlugins());
     }
 
-    public function getUpdatableThemes() {
+    /**
+     * Returns an array of Themes that can be updated.
+     * The Themes are extended with the `available` property that relies to the remote version
+     * @return Iterator Array of updatable Themes
+     */
+    public function getUpdatableThemes()
+    {
         $items      = [];
         $repository = $this->repository['themes'];
 
@@ -123,34 +220,75 @@ class GPM extends Iterator {
         }
 
         $this->cache[__METHOD__] = $items;
+
         return $items;
     }
 
-    public function isThemeUpdatable($theme) {
+    /**
+     * Checks if a Theme is Updatable
+     * @param  string  $theme The slug of the Theme
+     * @return boolean True if the Theme is updatable. False otherwise
+     */
+    public function isThemeUpdatable($theme)
+    {
         return array_key_exists($theme, $this->getUpdatableThemes());
     }
 
-    public function getRepositoryPlugin($slug) {
+    /**
+     * Returns a Plugin from the repository
+     * @param  string $slug The slug of the Plugin
+     * @return mixed  Package if found, NULL if not
+     */
+    public function getRepositoryPlugin($slug)
+    {
         return @$this->repository['plugins'][$slug];
     }
 
-    public function getRepositoryPlugins() {
+    /**
+     * Returns the list of Plugins available in the repository
+     * @return Iterator The Plugins remotely available
+     */
+    public function getRepositoryPlugins()
+    {
         return $this->repository['plugins'];
     }
 
-    public function getRepositoryTheme($slug) {
+    /**
+     * Returns a Theme from the repository
+     * @param  string $slug The slug of the Theme
+     * @return mixed  Package if found, NULL if not
+     */
+    public function getRepositoryTheme($slug)
+    {
         return @$this->repository['themes'][$slug];
     }
 
-    public function getRepositoryThemes() {
+    /**
+     * Returns the list of Themes available in the repository
+     * @return Iterator The Themes remotely available
+     */
+    public function getRepositoryThemes()
+    {
         return $this->repository['themes'];
     }
 
-    public function getRepository() {
+    /**
+     * Returns the list of Plugins and Themes available in the repository
+     * @return array Array of available Plugins and Themes
+     *               Format: ['plugins' => array, 'themes' => array]
+     */
+    public function getRepository()
+    {
         return $this->repository;
     }
 
-    public function findPackage($search) {
+    /**
+     * Searches for a Package in the repository
+     * @param  string  $search Can be either the slug or the name
+     * @return Package Package if found, FALSE if not
+     */
+    public function findPackage($search)
+    {
         $search = strtolower($search);
         if ($found = $this->getRepositoryTheme($search)) {
             return $found;
@@ -175,7 +313,19 @@ class GPM extends Iterator {
         return false;
     }
 
-    public function findPackages($searches = []) {
+    /**
+     * Returns the list of Plugins and Themes available in the repository
+     * @return array Array of available Plugins and Themes
+     *               Format: ['plugins' => array, 'themes' => array]
+     */
+    /**
+     * Searches for a list of Packages in the repository
+     * @param  array $searches An array of either slugs or names
+     * @return array Array of found Packages
+     *                        Format: ['total' => int, 'not_found' => array, <found-slugs>]
+     */
+    public function findPackages($searches = [])
+    {
         $packages = ['total' => 0, 'not_found' => []];
 
         foreach ($searches as $search) {