diff --git a/bl-kernel/dbcategories.class.php b/bl-kernel/dbcategories.class.php
new file mode 100644
index 00000000..bd35628c
--- /dev/null
+++ b/bl-kernel/dbcategories.class.php
@@ -0,0 +1,130 @@
+<?php defined('BLUDIT') or die('Bludit CMS.');
+
+/*
+Database structure
+- To re index the list of posts and pages need to be sorted
+
+{
+	"postsIndex": {
+		"videos": {
+			"name": "Videos",
+			"list": [ "first-post", "second-post" ]
+		},
+		"pets": {
+			"name": "Pets",
+			"list": [ "second-post", "another-post" ]
+		}
+	},
+	"pagesIndex": {
+		"videos": {
+			"name": "Videos",
+			"list": [ "first-post", "second-post" ]
+		},
+		"music": {
+			"name": "Music",
+			"list": [ "second-post", "another-post" ]
+		}
+	}
+}
+
+*/
+
+class dbCategories extends dbJSON
+{
+	public $dbFields = array(
+		'postsIndex'=>array('inFile'=>false, 'value'=>array()),
+		'pagesIndex'=>array('inFile'=>false, 'value'=>array())
+	);
+
+	function __construct()
+	{
+		parent::__construct(PATH_DATABASES.'categories.php');
+	}
+
+	private function getByCategory($type='postsIndex', $categorySlug, $amountPerPage, $pageNumber)
+	{
+		// Check if the category exists
+		if( !isset($this->db[$type][$categorySlug]) ) {
+			Log::set(__METHOD__.LOG_SEP.'Error getting '.$type.' by the category: '.$categorySlug);
+			return array();
+		}
+
+		$list = $this->db[$type][$categorySlug]['list'];
+
+		$init = (int) $amountPerPage * $pageNumber;
+		$end  = (int) min( ($init + $amountPerPage - 1), count($list) - 1 );
+		$outrange = $init<0 ? true : $init > $end;
+
+		if($outrange) {
+			Log::set(__METHOD__.LOG_SEP.'Error getting '.$type.' by the category, out of range, pageNumber: '.$pageNumber);
+			return array();
+		}
+
+		$tmp = array_flip($list);
+		return array_slice($tmp, $init, $amountPerPage, true);
+	}
+
+	public function getPagesByCategory($categorySlug, $amountPerPage, $pageNumber)
+	{
+		return $this->getByCategory('pagesIndex', $categorySlug, $amountPerPage, $pageNumber);
+	}
+
+	public function getPostsByCategory($categorySlug, $amountPerPage, $pageNumber)
+	{
+		return $this->getByCategory('postsIndex', $categorySlug, $amountPerPage, $pageNumber);
+	}
+
+	private function countByCategory($type='postsIndex', $categorySlug)
+	{
+		if( isset($this->db[$type][$categorySlug]) ) {
+			return count($this->db[$type][$categorySlug]['list']);
+		}
+
+		return 0;
+	}
+
+	public function countPostsByCategory($categorySlug)
+	{
+		return $this->countByCategory('postsIndex', $categorySlug);
+	}
+
+	public function countPagesByCategory($categorySlug)
+	{
+		return $this->countByCategory('pagesIndex', $categorySlug);
+	}
+
+	// Regenerate the posts index for each tag.
+	// (array) $db, the $db must be sorted by date and the posts published only.
+	public function reindexPosts($db)
+	{
+		$tagsIndex = array();
+
+		// Foreach post
+		foreach($db as $postKey=>$values)
+		{
+			$tags = $values['tags'];
+
+			// Foreach tag from post
+			foreach($tags as $tagKey=>$tagName)
+			{
+				if( isset($tagsIndex[$tagKey]) ) {
+					array_push($tagsIndex[$tagKey]['posts'], $postKey);
+				}
+				else {
+					$tagsIndex[$tagKey]['name'] = $tagName;
+					$tagsIndex[$tagKey]['posts'] = array($postKey);
+				}
+			}
+		}
+
+		$this->db['postsIndex'] = $tagsIndex;
+
+		if( $this->save() === false ) {
+			Log::set(__METHOD__.LOG_SEP.'Error occurred when trying to save the database file.');
+			return false;
+		}
+
+		return true;
+	}
+
+}
\ No newline at end of file