diff --git a/appinfo/database.xml b/appinfo/database.xml
new file mode 100644
index 000000000..daf4f51da
--- /dev/null
+++ b/appinfo/database.xml
@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<database>
+	<name>*dbname*</name>
+	<create>true</create>
+	<charset>utf8</charset>
+	<table>
+		<name>*dbprefix*notes_meta</name>
+		<declaration>
+			<field>
+				<name>id</name>
+				<type>integer</type>
+				<notnull>true</notnull>
+				<autoincrement>true</autoincrement>
+			</field>
+			<field>
+				<name>file_id</name>
+				<type>integer</type>
+				<notnull>true</notnull>
+			</field>
+			<field>
+				<name>user_id</name>
+				<type>text</type>
+				<notnull>true</notnull>
+				<length>64</length>
+			</field>
+			<field>
+				<name>last_update</name>
+				<type>integer</type>
+				<notnull>true</notnull>
+			</field>
+			<field>
+				<name>etag</name>
+				<type>text</type>
+				<notnull>true</notnull>
+				<length>32</length>
+			</field>
+			<index>
+				<name>notes_meta_file_id_index</name>
+				<field>
+					<name>file_id</name>
+				</field>
+			</index>
+			<index>
+				<name>notes_meta_user_id_index</name>
+				<field>
+					<name>user_id</name>
+				</field>
+			</index>
+			<index>
+				<name>notes_meta_file_id_user_id_index</name>
+				<unique>true</unique>
+				<field>
+					<name>file_id</name>
+					<name>user_id</name>
+				</field>
+			</index>
+		</declaration>
+	</table>
+</database>
diff --git a/controller/notesapicontroller.php b/controller/notesapicontroller.php
index 4f55b3f93..bcca536c6 100644
--- a/controller/notesapicontroller.php
+++ b/controller/notesapicontroller.php
@@ -12,10 +12,12 @@
 namespace OCA\Notes\Controller;
 
 use OCP\AppFramework\ApiController;
+use OCP\AppFramework\Http;
 use OCP\AppFramework\Http\DataResponse;
 use OCP\IRequest;
 
 use OCA\Notes\Service\NotesService;
+use OCA\Notes\Service\MetaService;
 use OCA\Notes\Db\Note;
 
 /**
@@ -29,6 +31,8 @@ class NotesApiController extends ApiController {
 
     /** @var NotesService */
     private $service;
+    /** @var MetaService */
+    private $metaService;
     /** @var string */
     private $userId;
 
@@ -38,10 +42,10 @@ class NotesApiController extends ApiController {
      * @param NotesService $service
      * @param string $UserId
      */
-    public function __construct($AppName, IRequest $request,
-                                NotesService $service, $UserId){
+    public function __construct($AppName, IRequest $request, NotesService $service, MetaService $metaService, $UserId) {
         parent::__construct($AppName, $request);
         $this->service = $service;
+        $this->metaService = $metaService;
         $this->userId = $UserId;
     }
 
@@ -52,7 +56,7 @@ public function __construct($AppName, IRequest $request,
      * notes
      * @return Note
      */
-    private function excludeFields(Note $note, array $exclude) {
+    private function excludeFields(Note &$note, array $exclude) {
         if(count($exclude) > 0) {
             foreach ($exclude as $field) {
                 if(property_exists($note, $field)) {
@@ -72,13 +76,28 @@ private function excludeFields(Note $note, array $exclude) {
      * @param string $exclude
      * @return DataResponse
      */
-    public function index($exclude='') {
+    public function index($exclude='', $pruneBefore=0) {
         $exclude = explode(',', $exclude);
+        $now = new \DateTime(); // this must be before loading notes if there are concurrent changes possible
         $notes = $this->service->getAll($this->userId);
+        $metas = $this->metaService->updateAll($this->userId, $notes);
         foreach ($notes as $note) {
-            $note = $this->excludeFields($note, $exclude);
+            $lastUpdate = $metas[$note->getId()]->getLastUpdate();
+            if($pruneBefore && $lastUpdate<$pruneBefore) {
+                $vars = get_object_vars($note);
+                unset($vars['id']);
+                $this->excludeFields($note, array_keys($vars));
+            } else {
+                $this->excludeFields($note, $exclude);
+            }
+        }
+        $etag = md5(json_encode($notes));
+        if ($this->request->getHeader('If-None-Match') === '"'.$etag.'"') {
+            return new DataResponse([], Http::STATUS_NOT_MODIFIED);
         }
-        return new DataResponse($notes);
+        return (new DataResponse($notes))
+            ->setLastModified($now)
+            ->setETag($etag);
     }
 
 
diff --git a/db/meta.php b/db/meta.php
new file mode 100644
index 000000000..44e34d00d
--- /dev/null
+++ b/db/meta.php
@@ -0,0 +1,32 @@
+<?php
+/**
+ * Nextcloud - Notes
+ *
+ * This file is licensed under the Affero General Public License version 3 or
+ * later. See the COPYING file.
+ */
+
+namespace OCA\Notes\Db;
+
+use OCP\AppFramework\Db\Entity;
+
+class Meta extends Entity {
+
+	public $userId;
+	public $fileId;
+	public $lastUpdate;
+	public $etag;
+
+	/**
+	 * @param Note $note
+	 * @return static
+	 */
+	public static function fromNote(Note $note, $userId) {
+		$meta = new static();
+		$meta->setUserId($userId);
+		$meta->setFileId($note->getId());
+		$meta->setLastUpdate(time());
+		$meta->setEtag($note->getEtag());
+		return $meta;
+	}
+}
diff --git a/db/metamapper.php b/db/metamapper.php
new file mode 100644
index 000000000..14d789eaf
--- /dev/null
+++ b/db/metamapper.php
@@ -0,0 +1,29 @@
+<?php
+/**
+ * Nextcloud - Notes
+ *
+ * This file is licensed under the Affero General Public License version 3 or
+ * later. See the COPYING file.
+ */
+
+namespace OCA\Notes\Db;
+
+use OCP\IDBConnection;
+use OCP\AppFramework\Db\Mapper;
+
+class MetaMapper extends Mapper {
+
+	public function __construct(IDBConnection $db) {
+		parent::__construct($db, 'notes_meta');
+	}
+
+	public function getAll($userId) {
+		$sql = 'SELECT * FROM `*PREFIX*notes_meta` WHERE user_id=?';
+		return $this->findEntities($sql, [$userId]);
+	}
+
+	public function get($userId, $fileId) {
+		$sql = 'SELECT * FROM `*PREFIX*notes_meta` WHERE user_id=? AND file_id=?';
+		return $this->findEntity($sql, [$userId, $fileId]);
+	}
+}
diff --git a/db/note.php b/db/note.php
index 31f32016b..f3536ce17 100644
--- a/db/note.php
+++ b/db/note.php
@@ -19,6 +19,8 @@
  * Class Note
  * @method integer getId()
  * @method void setId(integer $value)
+ * @method string getEtag()
+ * @method void setEtag(string $value)
  * @method integer getModified()
  * @method void setModified(integer $value)
  * @method string getTitle()
@@ -33,6 +35,7 @@
  */
 class Note extends Entity {
 
+    public $etag;
     public $modified;
     public $title;
     public $category;
@@ -60,6 +63,7 @@ public static function fromFile(File $file, Folder $notesFolder, $tags=[]){
             $note->setFavorite(true);
             //unset($tags[array_search(\OC\Tags::TAG_FAVORITE, $tags)]);
         }
+        $note->updateETag();
         $note->resetUpdatedFields();
         return $note;
     }
@@ -70,4 +74,16 @@ private static function convertEncoding($str) {
         }
         return $str;
     }
+
+    private function updateETag() {
+        // collect all relevant attributes
+        $data = '';
+        foreach(get_object_vars($this) as $key => $val) {
+            if($key!=='etag') {
+                $data .= $val;
+            }
+        }
+        $etag = md5($data);
+        $this->setEtag($etag);
+    }
 }
diff --git a/service/metaservice.php b/service/metaservice.php
new file mode 100644
index 000000000..1b5f47e11
--- /dev/null
+++ b/service/metaservice.php
@@ -0,0 +1,69 @@
+<?php
+/**
+ * Nextcloud - Notes
+ *
+ * This file is licensed under the Affero General Public License version 3 or
+ * later. See the COPYING file.
+ */
+
+namespace OCA\Notes\Service;
+
+use OCA\Notes\Db\Note;
+use OCA\Notes\Db\Meta;
+use OCA\Notes\Db\MetaMapper;
+
+/**
+ * Class MetaService
+ *
+ * @package OCA\Notes\Service
+ */
+class MetaService {
+
+	private $metaMapper;
+
+	public function __construct(MetaMapper $metaMapper) {
+		$this->metaMapper = $metaMapper;
+	}
+
+	public function updateAll($userId, Array $notes) {
+		$metas = $this->metaMapper->getAll($userId);
+		$metas = $this->getIndexedArray($metas, 'fileId');
+		$notes = $this->getIndexedArray($notes, 'id');
+		foreach($metas as $id=>$meta) {
+			if(!array_key_exists($id, $notes)) {
+				// DELETE obsolete notes
+				$this->metaMapper->delete($meta);
+				unset($metas[$id]);
+			}
+		}
+		foreach($notes as $id=>$note) {
+			if(!array_key_exists($id, $metas)) {
+				// INSERT new notes
+				$metas[$note->getId()] = $this->create($userId, $note);
+			} elseif($note->getEtag()!==$metas[$id]->getEtag()) {
+				// UPDATE changed notes
+				$meta = $metas[$id];
+				$this->updateIfNeeded($meta, $note);
+			}
+		}
+		return $metas;
+	}
+
+	private function getIndexedArray(array $data, $property) {
+		$property = ucfirst($property);
+		$getter = 'get'.$property;
+		$result = array();
+		foreach($data as $entity) {
+			$result[$entity->$getter()] = $entity;
+		}
+		return $result;
+	}
+
+	private function updateIfNeeded(&$meta, $note) {
+		if($note->getEtag()!==$meta->getEtag()) {
+			$meta->setEtag($note->getEtag());
+			$meta->setLastUpdate(time());
+			$this->metaMapper->update($meta);
+		}
+	}
+}
diff --git a/tests/unit/controller/NotesApiControllerTest.php b/tests/unit/controller/NotesApiControllerTest.php
index 3ce8cab6d..3f3feeab9 100644
--- a/tests/unit/controller/NotesApiControllerTest.php
+++ b/tests/unit/controller/NotesApiControllerTest.php
@@ -87,12 +87,14 @@ public function testGetAllHide(){
 
         $this->assertEquals(json_encode([
             [
+                'etag' => null,
                 'modified' => 123,
                 'category' => null,
                 'favorite' => false,
                 'id' => 3,
             ],
             [
+                'etag' => null,
                 'modified' => 111,
                 'category' => null,
                 'favorite' => false,
@@ -139,6 +141,7 @@ public function testGetHide(){
         $response = $this->controller->get(3, 'title,content');
 
         $this->assertEquals(json_encode([
+            'etag' => null,
             'modified' => 123,
             'category' => null,
             'favorite' => false,