diff --git a/assets/js/app.js b/assets/js/app.js
index 0d113850..6ad44053 100644
--- a/assets/js/app.js
+++ b/assets/js/app.js
@@ -23,6 +23,8 @@ import 'datatables.net-select-bs4/css/select.bootstrap4.css'
 import 'bootstrap-select/dist/css/bootstrap-select.css'
 import 'awesome-bootstrap-checkbox/awesome-bootstrap-checkbox.css'
 
+import "bootstrap-treeview/src/css/bootstrap-treeview.css"
+
 //require( 'jszip' );
 //#require( 'pdfmake' );
 require( 'datatables.net-bs4' );
@@ -33,10 +35,13 @@ require( 'datatables.net-buttons/js/buttons.print.js' );
 //require( 'datatables.net-colreorder-bs4' )();
 require( 'datatables.net-fixedheader-bs4' );
 require( 'datatables.net-select-bs4' );
-require('bootstrap-select')
+require('bootstrap-select');
 
+//require('bootstrap-treeview/src/js/bootstrap-treeview');
 
 //Define jquery globally
 window.$ = window.jQuery = require("jquery");
 
-//console.log('Hello Webpack Encore! Edit me in assets/js/app.js');
+require('bootstrap-treeview/src/js/bootstrap-treeview');
+
+//console.log('Hello Webpack Encore! Edit me in assets/js/app.js');
\ No newline at end of file
diff --git a/package.json b/package.json
index 5b4b84c9..e61ff559 100644
--- a/package.json
+++ b/package.json
@@ -19,6 +19,7 @@
         "@ckeditor/ckeditor5-build-classic": "^12.0.0",
         "awesome-bootstrap-checkbox": "^1.0.1",
         "bootstrap-select": "^1.13.8",
+        "bootstrap-treeview": "jbtronics/bootstrap-treeview",
         "datatables.net-bs4": "^1.10.19",
         "datatables.net-buttons-bs4": "^1.5.4",
         "datatables.net-fixedheader-bs4": "^3.1.5",
diff --git a/src/Controller/TreeBuilder.php b/src/Controller/TreeBuilder.php
new file mode 100644
index 00000000..2545c429
--- /dev/null
+++ b/src/Controller/TreeBuilder.php
@@ -0,0 +1,104 @@
+<?php
+/**
+ * part-db version 0.1
+ * Copyright (C) 2005 Christoph Lechner
+ * http://www.cl-projects.de/.
+ *
+ * part-db version 0.2+
+ * Copyright (C) 2009 K. Jacobs and others (see authors.php)
+ * http://code.google.com/p/part-db/
+ *
+ * Part-DB Version 0.4+
+ * Copyright (C) 2016 - 2019 Jan Böhmer
+ * https://github.com/jbtronics
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+namespace App\Controller;
+
+use App\Entity\StructuralDBElement;
+use App\Helpers\TreeViewNode;
+use App\Repository\StructuralDBElementRepository;
+use App\Services\EntityURLGenerator;
+use App\Services\ToolsTreeBuilder;
+use Doctrine\ORM\EntityManagerInterface;
+
+/**
+ *  This service gives you multiple possibilities to generate trees.
+ *
+ * @package App\Controller
+ */
+class TreeBuilder
+{
+    protected $url_generator;
+    protected $em;
+
+    public function __construct(EntityURLGenerator $URLGenerator, EntityManagerInterface $em)
+    {
+        $this->url_generator = $URLGenerator;
+        $this->em = $em;
+    }
+
+    /**
+     * Generates a tree for the given Element. The given element is the top node, all children are child nodes.
+     * @param StructuralDBElement $element The element for which the tree should be generated.
+     * @param string $href_type The type of the links that should be used for the links. Set to null, to disable links.
+     *                          See EntityURLGenerator::getURL for possible types.
+     * @return TreeViewNode The Node for the given Element.
+     */
+    public function elementToTreeNode(StructuralDBElement $element, string $href_type = 'list_parts') : TreeViewNode
+    {
+        $children = $element->getSubelements();
+
+        $children_nodes = null;
+        foreach ($children as $child) {
+            $children_nodes[] = $this->elementToTreeNode($child);
+        }
+
+        //Check if we need to generate a href type
+        $href = null;
+
+        if (!empty($href_type)) {
+            $href = $this->url_generator->getURL($element, $href_type);
+        }
+
+        return new TreeViewNode($element->getName(), $href, $children_nodes);
+    }
+
+    /**
+     * Generates a tree for all elements of the given type
+     * @param StructuralDBElement $class_name The class name of the StructuralDBElement class for which the tree should
+     *                                          be generated.
+     * @param string $href_type The type of the links that should be used for the links. Set to null, to disable links.
+     *                          See EntityURLGenerator::getURL for possible types.
+     * @return TreeViewNode[] Returns an array, containing all nodes. It is empty if the given class has no elements.
+     */
+    public function typeToTree(StructuralDBElement $class_name, string $href_type = 'list_parts') : array
+    {
+        /**
+         * @var $repo StructuralDBElementRepository
+         */
+        $repo = $this->em->getRepository($class_name);
+        $root_nodes = $repo->findRootNodes();
+
+        $array = array();
+        foreach ($root_nodes as $node) {
+            $array = $this->elementToTreeNode($node, $href_type);
+        }
+
+        return $array;
+    }
+}
diff --git a/src/Controller/TreeController.php b/src/Controller/TreeController.php
new file mode 100644
index 00000000..10898734
--- /dev/null
+++ b/src/Controller/TreeController.php
@@ -0,0 +1,74 @@
+<?php
+/**
+ * part-db version 0.1
+ * Copyright (C) 2005 Christoph Lechner
+ * http://www.cl-projects.de/.
+ *
+ * part-db version 0.2+
+ * Copyright (C) 2009 K. Jacobs and others (see authors.php)
+ * http://code.google.com/p/part-db/
+ *
+ * Part-DB Version 0.4+
+ * Copyright (C) 2016 - 2019 Jan Böhmer
+ * https://github.com/jbtronics
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+namespace App\Controller;
+
+use App\Entity\Category;
+use App\Helpers\TreeViewNode;
+use App\Services\ToolsTreeBuilder;
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\Routing\Annotation\Route;
+
+/**
+ * This controller has the purpose to provide the data for all treeviews.
+ *
+ * @package App\Controller
+ */
+class TreeController extends AbstractController
+{
+    /**
+     * @Route("/tree/tools/", name="tree_tools")
+     */
+    public function tools(ToolsTreeBuilder $builder)
+    {
+        $tree = $builder->getTree();
+
+        //Ignore null values, to save data
+        return $this->json($tree, 200, [], ['skip_null_values' => true]);
+    }
+
+    /**
+     * @Route("/tree/category/{id}", name="tree_category")
+     */
+    public function categoryTree(TreeBuilder $builder, Category $category = null)
+    {
+        if($category != null) {
+            $tree[] = $builder->elementToTreeNode($category);
+        } else {
+            $tree = $builder->typeToTree(Category::class);
+        }
+
+
+        return $this->json($tree, 200, [], ['skip_null_values' => true]);
+    }
+
+
+
+
+}
diff --git a/src/Entity/StructuralDBElement.php b/src/Entity/StructuralDBElement.php
index b10e6946..8390e69d 100644
--- a/src/Entity/StructuralDBElement.php
+++ b/src/Entity/StructuralDBElement.php
@@ -37,6 +37,7 @@ use Doctrine\ORM\PersistentCollection;
  * an attribute of a root element, you will get an exception!
  *
  * @ORM\MappedSuperclass()
+ * //@ORM\Entity(repositoryClass="App\Repository\StructuralDBElementRepository")
  */
 abstract class StructuralDBElement extends AttachmentContainingDBElement
 {
@@ -207,23 +208,9 @@ abstract class StructuralDBElement extends AttachmentContainingDBElement
      *
      * @return static[] all subelements as an array of objects (sorted by their full path)
      */
-    public function getSubelements(bool $recursive): PersistentCollection
+    public function getSubelements(): PersistentCollection
     {
-        if (null == $this->children) {
-            $this->children = new ArrayCollection();
-        }
-
-        if (!$recursive) {
-            return $this->children;
-        }
-
-        $all_elements = array();
-        foreach ($this->children as $subelement) {
-            $all_elements[] = $subelement;
-            $all_elements = array_merge($all_elements, $subelement->getSubelements(true));
-        }
-
-        return $all_elements;
+        return $this->children;
     }
 
     /******************************************************************************
diff --git a/src/Helpers/TreeViewNode.php b/src/Helpers/TreeViewNode.php
new file mode 100644
index 00000000..ac282680
--- /dev/null
+++ b/src/Helpers/TreeViewNode.php
@@ -0,0 +1,118 @@
+<?php
+/**
+ * part-db version 0.1
+ * Copyright (C) 2005 Christoph Lechner
+ * http://www.cl-projects.de/.
+ *
+ * part-db version 0.2+
+ * Copyright (C) 2009 K. Jacobs and others (see authors.php)
+ * http://code.google.com/p/part-db/
+ *
+ * Part-DB Version 0.4+
+ * Copyright (C) 2016 - 2019 Jan Böhmer
+ * https://github.com/jbtronics
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+namespace App\Helpers;
+
+/**
+ * This class represents a node for the bootstrap treeview node.
+ * When you serialize an array of these objects to JSON, you can use the serialized data in data for the treeview.
+ * @package App\Helpers
+ */
+class TreeViewNode
+{
+    protected $text;
+    protected $href;
+    protected $nodes;
+
+    /**
+     * Creates a new TreeView node with the given parameters.
+     * @param string $text The text that is shown in the node. (e.g. the name of the node)
+     * @param string|null $href A link for the node. You have to activate "enableLinks" option in init of the treeview.
+     *                          Set this to null, if no href should be used.
+     * @param array|null $nodes An array containing other TreeViewNodes. They will be used as children nodes of the
+     *                          newly created nodes. Set to null, if it should not have children.
+     */
+    public function __construct(string $text, ?string $href = null, ?array $nodes = null)
+    {
+        $this->text = $text;
+        $this->href = $href;
+        $this->nodes = $nodes;
+    }
+
+    /**
+     * Returns the node text.
+     * @return string
+     */
+    public function getText(): string
+    {
+        return $this->text;
+    }
+
+    /**
+     * Sets the node text
+     * @param string $text The new node text.
+     * @return TreeViewNode
+     */
+    public function setText(string $text): self
+    {
+        $this->text = $text;
+        return $this;
+    }
+
+    /**
+     * Returns the href link.
+     * @return string|null
+     */
+    public function getHref(): ?string
+    {
+        return $this->href;
+    }
+
+    /**
+     * Sets the href link.
+     * @param string|null $href The new href link.
+     * @return TreeViewNode
+     */
+    public function setHref(?string $href): self
+    {
+        $this->href = $href;
+        return $this;
+    }
+
+    /**
+     * Returns the children nodes of this node.
+     * @return array|null
+     */
+    public function getNodes(): ?array
+    {
+        return $this->nodes;
+    }
+
+    /**
+     * Sets the children nodes.
+     * @param array|null $nodes The new children nodes
+     * @return TreeViewNode
+     */
+    public function setNodes(?array $nodes): self
+    {
+        $this->nodes = $nodes;
+        return $this;
+    }
+
+}
diff --git a/src/Repository/StructuralDBElementRepository.php b/src/Repository/StructuralDBElementRepository.php
new file mode 100644
index 00000000..9f952888
--- /dev/null
+++ b/src/Repository/StructuralDBElementRepository.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ *
+ * part-db version 0.1
+ * Copyright (C) 2005 Christoph Lechner
+ * http://www.cl-projects.de/
+ *
+ * part-db version 0.2+
+ * Copyright (C) 2009 K. Jacobs and others (see authors.php)
+ * http://code.google.com/p/part-db/
+ *
+ * Part-DB Version 0.4+
+ * Copyright (C) 2016 - 2019 Jan Böhmer
+ * https://github.com/jbtronics
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ *
+ */
+
+namespace App\Repository;
+
+
+use App\Entity\StructuralDBElement;
+use Doctrine\Common\Collections\Criteria;
+use Doctrine\ORM\EntityRepository;
+
+class StructuralDBElementRepository extends EntityRepository
+{
+
+    /**
+     * Finds all nodes without a parent node. They are our root nodes.
+     *
+     * @return StructuralDBElement[]
+     */
+    public function findRootNodes() : array
+    {
+        return $this->findBy(['parent' => null]);
+    }
+
+}
\ No newline at end of file
diff --git a/src/Services/EntityURLGenerator.php b/src/Services/EntityURLGenerator.php
index c309ea9f..c94a2c91 100644
--- a/src/Services/EntityURLGenerator.php
+++ b/src/Services/EntityURLGenerator.php
@@ -29,6 +29,7 @@
 
 namespace App\Services;
 
+use App\Entity\Category;
 use App\Entity\NamedDBElement;
 use App\Entity\Part;
 use App\Exceptions\EntityNotSupported;
@@ -46,13 +47,41 @@ class EntityURLGenerator
         $this->urlGenerator = $urlGenerator;
     }
 
+    /**
+     * Generates an URL to the page using the given page type and element.
+     * For the given types, the [type]URL() functions are called (e.g. infoURL()).
+     * Not all entity class and $type combinations are supported.
+     *
+     * @param $entity mixed The element for which the page should be generated.
+     * @param string $type The page type. Currently supported: 'info', 'edit', 'create', 'clone', 'list'/'list_parts'
+     * @return string The link to the desired page.
+     * @throws EntityNotSupported Thrown if the entity is not supported for the given type.
+     * @throws \InvalidArgumentException Thrown if the givent type is not existing.
+     */
+    public function getURL($entity, string $type)
+    {
+        switch ($type) {
+            case 'info':
+                return $this->infoURL($entity);
+            case 'edit':
+                return $this->editURL($entity);
+            case 'create':
+                return $this->createURL($entity);
+            case 'clone':
+                return $this->cloneURL($entity);
+            case 'list':
+            case 'list_parts':
+                return $this->listPartsURL($entity);
+        }
+
+        throw new \InvalidArgumentException('Method is not supported!');
+    }
+
     /**
      * Generates an URL to a page, where info about this entity can be viewed.
      *
      * @param $entity mixed The entity for which the info should be generated.
-     *
      * @return string The URL to the info page
-     *
      * @throws EntityNotSupported If the method is not supported for the given Entity
      */
     public function infoURL($entity): string
@@ -65,6 +94,13 @@ class EntityURLGenerator
         throw new EntityNotSupported('The given entity is not supported yet!');
     }
 
+    /**
+     * Generates an URL to a page, where this entity can be edited.
+     *
+     * @param $entity mixed The entity for which the edit link should be generated.
+     * @return string The URL to the edit page.
+     * @throws EntityNotSupported If the method is not supported for the given Entity
+     */
     public function editURL($entity): string
     {
         if ($entity instanceof Part) {
@@ -75,6 +111,13 @@ class EntityURLGenerator
         throw new EntityNotSupported('The given entity is not supported yet!');
     }
 
+    /**
+     * Generates an URL to a page, where a entity of this type can be created.
+     *
+     * @param $entity mixed The entity for which the link should be generated.
+     * @return string The URL to the page.
+     * @throws EntityNotSupported If the method is not supported for the given Entity
+     */
     public function createURL($entity): string
     {
         if ($entity instanceof Part) {
@@ -84,6 +127,14 @@ class EntityURLGenerator
         throw new EntityNotSupported('The given entity is not supported yet!');
     }
 
+    /**
+     * Generates an URL to a page, where a new entity can be created, that has the same informations as the
+     * given entity (element cloning)
+     *
+     * @param $entity mixed The entity for which the link should be generated.
+     * @return string The URL to the page.
+     * @throws EntityNotSupported If the method is not supported for the given Entity
+     */
     public function cloneURL($entity): string
     {
         if ($entity instanceof Part) {
@@ -93,6 +144,22 @@ class EntityURLGenerator
         throw new EntityNotSupported('The given entity is not supported yet!');
     }
 
+    /**
+     * Generates an URL to a page, where all parts are listed, which are contained in the given element.
+     *
+     * @param $entity mixed The entity for which the link should be generated.
+     * @return string The URL to the page.
+     * @throws EntityNotSupported If the method is not supported for the given Entity
+     */
+    public function listPartsURL($entity) : string
+    {
+        if ($entity instanceof Category) {
+            return $this->urlGenerator->generate('app_partlists_showcategory', ['id' => $entity->getID()]);
+        }
+        throw new EntityNotSupported('The given entity is not supported yet!');
+
+    }
+
     /**
      * Generates an HTML link to the info page about the given entity.
      *
diff --git a/src/Services/ToolsTreeBuilder.php b/src/Services/ToolsTreeBuilder.php
new file mode 100644
index 00000000..c00238ab
--- /dev/null
+++ b/src/Services/ToolsTreeBuilder.php
@@ -0,0 +1,57 @@
+<?php
+/**
+ * part-db version 0.1
+ * Copyright (C) 2005 Christoph Lechner
+ * http://www.cl-projects.de/.
+ *
+ * part-db version 0.2+
+ * Copyright (C) 2009 K. Jacobs and others (see authors.php)
+ * http://code.google.com/p/part-db/
+ *
+ * Part-DB Version 0.4+
+ * Copyright (C) 2016 - 2019 Jan Böhmer
+ * https://github.com/jbtronics
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+namespace App\Services;
+
+use App\Helpers\TreeViewNode;
+
+/**
+ * This Service generates the tree structure for the tools.
+ * @package App\Services
+ */
+class ToolsTreeBuilder
+{
+
+    /**
+     * Generates the tree for the tools menu.
+     * @return TreeViewNode The array containing all Nodes for the tools menu.
+     */
+    public function getTree() : array
+    {
+        //TODO: Use proper values
+
+        $nodes = array();
+        $nodes[] = new TreeViewNode('Node 1');
+        $nodes[] = new TreeViewNode('Node 2');
+
+        $tree[] = new TreeViewNode('test', 'www.google.de', $nodes);
+
+        return $tree;
+    }
+}
diff --git a/src/Twig/AppExtension.php b/src/Twig/AppExtension.php
index ed2e6da4..4f0fcfca 100644
--- a/src/Twig/AppExtension.php
+++ b/src/Twig/AppExtension.php
@@ -57,18 +57,7 @@ class AppExtension extends AbstractExtension
 
     public function generateEntityURL(DBElement $entity, string $method = 'info'): string
     {
-        switch ($method) {
-            case 'info':
-                return $this->entityURLGenerator->infoURL($entity);
-            case 'edit':
-                return $this->entityURLGenerator->editURL($entity);
-            case 'create':
-                return $this->entityURLGenerator->createURL($entity);
-            case 'clone':
-                return $this->entityURLGenerator->cloneURL($entity);
-        }
-
-        throw new \InvalidArgumentException('method is not supported!');
+        return $this->entityURLGenerator->getURL($entity, $method);
     }
 
     public function parseBBCode(string $bbcode): string
diff --git a/templates/base.html.twig b/templates/base.html.twig
index be783c1d..05b0ee2f 100644
--- a/templates/base.html.twig
+++ b/templates/base.html.twig
@@ -309,6 +309,24 @@
 
 {% endblock %}
 
+
+<script>
+    $.getJSON("{{ path("tree_tools") }}",null, function (data) {
+        $('#tree-tools').treeview({
+            data: data,
+            showIcon: false
+        });
+    });
+
+    $.getJSON("{{ path("tree_category", {"id": 1}) }}",null, function (data) {
+        $('#tree-categories').treeview({
+            data: data,
+            showIcon: false,
+            enableLinks: true
+        });
+    });
+</script>
+
 {% block scripts %}
 
 {% endblock %}
diff --git a/webpack.config.js b/webpack.config.js
index 2f7e205c..23356009 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -48,7 +48,7 @@ Encore
     //.enableTypeScriptLoader()
 
     // uncomment if you're having problems with a jQuery plugin
-    //.autoProvidejQuery()
+    .autoProvidejQuery()
 
     // uncomment if you use API Platform Admin (composer req api-admin)
     //.enableReactPreset()
diff --git a/yarn.lock b/yarn.lock
index e3644fce..356e568a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1195,6 +1195,10 @@ bootstrap-select@^1.13.8:
   resolved "https://registry.yarnpkg.com/bootstrap-select/-/bootstrap-select-1.13.8.tgz#c47047410511f6d8a8917a7738d1b03c95717d5d"
   integrity sha512-WF6GJPgb98cv75X6/zoCWUNwM/HPoYKP6JDBryTNDCHMPV9YyMqU7xXncC7Se2M5VAt7kZQ/i2GSYwaf5Q/Z3w==
 
+bootstrap-treeview@jbtronics/bootstrap-treeview:
+  version "1.2.1"
+  resolved "https://codeload.github.com/jbtronics/bootstrap-treeview/tar.gz/0855394d4fa06c99289d2ba9a164a987228456c5"
+
 bootstrap@^4.3.1:
   version "4.3.1"
   resolved "https://registry.yarnpkg.com/bootstrap/-/bootstrap-4.3.1.tgz#280ca8f610504d99d7b6b4bfc4b68cec601704ac"