diff --git a/run-tests.sh b/run-tests.sh
new file mode 100755
index 00000000..ff0959d1
--- /dev/null
+++ b/run-tests.sh
@@ -0,0 +1,2 @@
+#!/bin/sh
+phpunit --strict --bootstrap src/AutoLoader.php tests/
diff --git a/src/AutoLoader.php b/src/AutoLoader.php
new file mode 100644
index 00000000..0e2cfbfc
--- /dev/null
+++ b/src/AutoLoader.php
@@ -0,0 +1,24 @@
+<?php
+namespace Szurubooru;
+
+final class AutoLoader
+{
+	public static function init()
+	{
+		spl_autoload_register([__CLASS__, '_include']);
+	}
+
+	public static function _include($className)
+	{
+		$className = str_replace('\\', DIRECTORY_SEPARATOR, $className);
+		$className = str_replace('Szurubooru', '', $className);
+		if (strpos($className, 'Tests') !== false)
+			$className = dirname(__DIR__) . DIRECTORY_SEPARATOR . str_replace('Tests', 'tests', $className);
+		else
+			$className = __DIR__ . DIRECTORY_SEPARATOR . $className;
+		$className .= '.php';
+		include $className;
+	}
+}
+
+AutoLoader::init();
diff --git a/src/Dao/AbstractDao.php b/src/Dao/AbstractDao.php
new file mode 100644
index 00000000..639b8bd1
--- /dev/null
+++ b/src/Dao/AbstractDao.php
@@ -0,0 +1,81 @@
+<?php
+namespace Szurubooru\Dao;
+
+abstract class AbstractDao implements ICrudDao
+{
+	protected $db;
+	protected $collection;
+	protected $entityName;
+
+	public function __construct(\MongoDB $mongoDb, $collectionName, $entityName)
+	{
+		$this->db = $mongoDb;
+		$this->collection = $mongoDb->selectCollection($collectionName);
+		$this->entityName = $entityName;
+	}
+
+	public function save(&$entity)
+	{
+		$arrayEntity = $this->makeArray($entity);
+		if ($entity->id)
+		{
+			unset ($arrayEntity['_id']);
+			$this->collection->update(['_id' => new \MongoId($entity->id)], $arrayEntity, ['safe' => true]);
+		}
+		else
+		{
+			$this->collection->insert($arrayEntity, ['safe' => true]);
+		}
+		$entity = $this->makeEntity($arrayEntity);
+		return $entity;
+	}
+
+	public function getAll()
+	{
+		$entities = [];
+		foreach ($this->collection->find() as $key => $arrayEntity)
+		{
+			$entity = $this->makeEntity($arrayEntity);
+			$entities[$key] = $entity;
+		}
+		return $entities;
+	}
+
+	public function getById($postId)
+	{
+		$arrayEntity = $this->collection->findOne(['_id' => new \MongoId($postId)]);
+		return $this->makeEntity($arrayEntity);
+	}
+
+	public function deleteAll()
+	{
+		$this->collection->remove();
+	}
+
+	public function deleteById($postId)
+	{
+		$this->collection->remove(['_id' => new \MongoId($postId)]);
+	}
+
+	private function makeArray($entity)
+	{
+		$arrayEntity = (array) $entity;
+		if (isset($entity->id))
+		{
+			$arrayEntity['_id'] = $arrayEntity['id'];
+			unset($arrayEntity['id']);
+		}
+		return $arrayEntity;
+	}
+
+	private function makeEntity($arrayEntity)
+	{
+		$entity = \Szurubooru\Helpers\TypeHelper::arrayToClass($arrayEntity, $this->entityName);
+		if (isset($entity->_id))
+		{
+			$entity->id = (string) $entity->_id;
+			unset($entity->_id);
+		}
+		return $entity;
+	}
+}
diff --git a/src/Dao/ICrudDao.php b/src/Dao/ICrudDao.php
new file mode 100644
index 00000000..ae3a0c13
--- /dev/null
+++ b/src/Dao/ICrudDao.php
@@ -0,0 +1,15 @@
+<?php
+namespace Szurubooru\Dao;
+
+interface ICrudDao
+{
+	public function getAll();
+
+	public function getById($objectId);
+
+	public function save(&$object);
+
+	public function deleteById($objectId);
+
+	public function deleteAll();
+}
diff --git a/src/Dao/PostDao.php b/src/Dao/PostDao.php
new file mode 100644
index 00000000..8d19e28a
--- /dev/null
+++ b/src/Dao/PostDao.php
@@ -0,0 +1,10 @@
+<?php
+namespace Szurubooru\Dao;
+
+final class PostDao extends AbstractDao implements ICrudDao
+{
+	public function __construct(\MongoDB $mongoDb)
+	{
+		parent::__construct($mongoDb, 'posts', '\Szurubooru\Entities\Post');
+	}
+}
diff --git a/src/Entities/Entity.php b/src/Entities/Entity.php
new file mode 100644
index 00000000..57782749
--- /dev/null
+++ b/src/Entities/Entity.php
@@ -0,0 +1,7 @@
+<?php
+namespace Szurubooru\Entities;
+
+abstract class Entity
+{
+	public $id = null;
+}
diff --git a/src/Entities/Post.php b/src/Entities/Post.php
new file mode 100644
index 00000000..02f2e5a5
--- /dev/null
+++ b/src/Entities/Post.php
@@ -0,0 +1,7 @@
+<?php
+namespace Szurubooru\Entities;
+
+final class Post extends Entity
+{
+	public $name;
+}
diff --git a/src/Entities/Tag.php b/src/Entities/Tag.php
new file mode 100644
index 00000000..7d7e2bfe
--- /dev/null
+++ b/src/Entities/Tag.php
@@ -0,0 +1,8 @@
+<?php
+namespace Szurubooru\Entities;
+
+final class Tag extends Entity
+{
+	public $name;
+	public $usages;
+}
diff --git a/src/Helpers/TypeHelper.php b/src/Helpers/TypeHelper.php
new file mode 100644
index 00000000..bc4231ee
--- /dev/null
+++ b/src/Helpers/TypeHelper.php
@@ -0,0 +1,20 @@
+<?php
+namespace Szurubooru\Helpers;
+
+final class TypeHelper
+{
+	public static function arrayToClass($array, $className)
+	{
+		if (!$array)
+			return null;
+
+		if (!class_exists($className, true))
+			return null;
+
+		return unserialize(
+			preg_replace(
+				'/^O:[0-9]+:"[^"]+":/i',
+				'O:' . strlen($className) . ':"'  . $className . '":',
+				serialize((object) $array)));
+	}
+}
diff --git a/src/UpgradeService.php b/src/UpgradeService.php
new file mode 100644
index 00000000..b563cb7e
--- /dev/null
+++ b/src/UpgradeService.php
@@ -0,0 +1,29 @@
+<?php
+namespace Szurubooru;
+
+final class UpgradeService
+{
+	private $db;
+
+	public function __construct(\MongoDB $db)
+	{
+		$this->db = $db;
+	}
+
+	public function prepareForUsage()
+	{
+		$this->db->createCollection('posts');
+	}
+
+	public function removeAllData()
+	{
+		foreach ($this->db->getCollectionNames() as $collectionName)
+			$this->removeCollectionData($collectionName);
+	}
+
+	private function removeCollectionData($collectionName)
+	{
+		$this->db->$collectionName->remove();
+		$this->db->$collectionName->deleteIndexes();
+	}
+}
diff --git a/tests/AbstractDatabaseTest.php b/tests/AbstractDatabaseTest.php
new file mode 100644
index 00000000..b6399ed8
--- /dev/null
+++ b/tests/AbstractDatabaseTest.php
@@ -0,0 +1,26 @@
+<?php
+namespace Szurubooru\Tests;
+
+abstract class AbstractDatabaseTest extends \PHPUnit_Framework_TestCase
+{
+	protected $db;
+	protected $connection;
+	protected $upgradeService;
+
+	public function setUp()
+	{
+		$host = 'localhost';
+		$port = 27017;
+		$database = 'test';
+		$connectingString = sprintf('mongodb://%s:%d/%s', $host, $port, $database);
+		$this->connection = new \Mongo($connectingString);
+		$this->db = $this->connection->selectDb($database);
+		$this->upgradeService = new \Szurubooru\UpgradeService($this->db);
+		$this->upgradeService->prepareForUsage();
+	}
+
+	public function tearDown()
+	{
+		$this->upgradeService->removeAllData();
+	}
+}
diff --git a/tests/Dao/PostDaoTest.php b/tests/Dao/PostDaoTest.php
new file mode 100644
index 00000000..cc63fa38
--- /dev/null
+++ b/tests/Dao/PostDaoTest.php
@@ -0,0 +1,105 @@
+<?php
+namespace Szurubooru\Tests\Dao;
+
+final class PostDaoTest extends \Szurubooru\Tests\AbstractDatabaseTest
+{
+	public function testSaving()
+	{
+		$postDao = new \Szurubooru\Dao\PostDao($this->db);
+
+		$post = new \Szurubooru\Entities\Post();
+		$post->name = 'test2';
+
+		$postDao->save($post);
+		$post->name .= '3';
+		$postDao->save($post);
+
+		$otherPost = new \Szurubooru\Entities\Post();
+		$otherPost->name = 'yo';
+		$postDao->save($otherPost);
+
+		$this->assertEquals('test23', $post->name);
+		$this->assertEquals('yo', $otherPost->name);
+	}
+
+	public function testGettingAll()
+	{
+		$postDao = new \Szurubooru\Dao\PostDao($this->db);
+
+		$post1 = new \Szurubooru\Entities\Post();
+		$post1->name = 'test2';
+		$post2 = new \Szurubooru\Entities\Post();
+		$post2->name = 'test2';
+
+		$postDao->save($post1);
+		$postDao->save($post2);
+
+		$actual = $postDao->getAll();
+		$expected = [
+			$post1->id => $post1,
+			$post2->id => $post2,
+		];
+
+		$this->assertEquals($expected, $actual);
+	}
+
+	public function testGettingById()
+	{
+		$postDao = new \Szurubooru\Dao\PostDao($this->db);
+
+		$post1 = new \Szurubooru\Entities\Post();
+		$post1->name = 'test2';
+		$post2 = new \Szurubooru\Entities\Post();
+		$post2->name = 'test2';
+
+		$postDao->save($post1);
+		$postDao->save($post2);
+
+		$actualPost1 = $postDao->getById($post1->id);
+		$actualPost2 = $postDao->getById($post2->id);
+		$this->assertEquals($post1, $actualPost1);
+		$this->assertEquals($post2, $actualPost2);
+	}
+
+	public function testDeletingAll()
+	{
+		$postDao = new \Szurubooru\Dao\PostDao($this->db);
+
+		$post1 = new \Szurubooru\Entities\Post();
+		$post1->name = 'test2';
+		$post2 = new \Szurubooru\Entities\Post();
+		$post2->name = 'test2';
+
+		$postDao->save($post1);
+		$postDao->save($post2);
+
+		$postDao->deleteAll();
+
+		$actualPost1 = $postDao->getById($post1->id);
+		$actualPost2 = $postDao->getById($post2->id);
+		$this->assertEquals(null, $actualPost1);
+		$this->assertEquals(null, $actualPost2);
+		$this->assertEquals(0, count($postDao->getAll()));
+	}
+
+	public function testDeletingById()
+	{
+		$postDao = new \Szurubooru\Dao\PostDao($this->db);
+
+		$post1 = new \Szurubooru\Entities\Post();
+		$post1->name = 'test2';
+		$post2 = new \Szurubooru\Entities\Post();
+		$post2->name = 'test2';
+
+		$postDao->save($post1);
+		$postDao->save($post2);
+
+		$postDao->deleteById($post1->id);
+
+		$actualPost1 = $postDao->getById($post1->id);
+		$actualPost2 = $postDao->getById($post2->id);
+		$this->assertEquals(null, $actualPost1);
+		$this->assertEquals($actualPost2, $actualPost2);
+		$this->assertEquals(1, count($postDao->getAll()));
+	}
+}