diff --git a/inc/api.php b/inc/api.php
new file mode 100644
index 00000000..5592d8af
--- /dev/null
+++ b/inc/api.php
@@ -0,0 +1,123 @@
+<?php
+
+/*
+ *  Copyright (c) 2010-2013 Tinyboard Development Group
+ */
+
+/**
+ * Class for generating json API compatible with 4chan API
+ */
+class Api {
+
+	/**
+	 * Translation from local fields to fields in 4chan-style API
+	 */
+	public static $postFields = array(
+		'id' => 'no',
+		'thread' => 'resto',
+		'subject' => 'sub',
+		'email' => 'email',
+		'name' => 'name',
+		'trip' => 'trip',
+		'capcode' => 'capcode',
+		'body' => 'com',
+		'time' => 'time',
+		'thumb' => 'thumb', // non-compatible field
+		'thumbx' => 'tn_w',
+		'thumby' => 'tn_h',
+		'file' => 'file', // non-compatible field
+		'filex' => 'w',
+		'filey' => 'h',
+		'filesize' => 'fsize',
+		//'filename' => 'filename',
+		'omitted' => 'omitted_posts',
+		'omitted_images' => 'omitted_images',
+		//'posts' => 'replies',
+		//'ip' => '',
+		'sticky' => 'sticky',
+		'locked' => 'locked',
+		//'bumplocked' => '',
+		//'embed' => '',
+		//'root' => '',
+		//'mod' => '',
+		//'hr' => '',
+	);
+
+	static $ints = array(
+		'no' => 1,
+		'resto' => 1,
+		'time' => 1,
+		'tn_w' => 1,
+		'tn_h' => 1,
+		'w' => 1,
+		'h' => 1,
+		'fsize' => 1,
+		'omitted_posts' => 1,
+		'omitted_images' => 1,
+		'sticky' => 1,
+		'locked' => 1,
+	);
+
+	private function translatePost($post) {
+		$apiPost = array();
+		foreach (self::$postFields as $local => $translated) {
+			if (!isset($post->$local))
+				continue;
+
+			$toInt = isset(self::$ints[$translated]);
+			$val = $post->$local;
+			if ($val !== null && $val !== '') {
+				$apiPost[$translated] = $toInt ? (int) $val : $val;
+			}
+		}
+
+		if (isset($post->filename)) {
+			$dotPos = strrpos($post->filename, '.');
+			$apiPost['filename'] = substr($post->filename, 0, $dotPos);
+			$apiPost['ext'] = substr($post->filename, $dotPos);
+		}
+
+		return $apiPost;
+	}
+
+	function translateThread(Thread $thread) {
+		$apiPosts = array();
+		$op = $this->translatePost($thread);
+		$op['resto'] = 0;
+		$apiPosts['posts'][] = $op;
+
+		foreach ($thread->posts as $p) {
+			$apiPosts['posts'][] = $this->translatePost($p);
+		}
+
+		return $apiPosts;
+	}
+
+	function translatePage(array $threads) {
+		$apiPage = array();
+		foreach ($threads as $thread) {
+			$apiPage['threads'][] = $this->translateThread($thread);
+		}
+		return $apiPage;
+	}
+
+	function translateCatalogPage(array $threads) {
+		$apiPage = array();
+		foreach ($threads as $thread) {
+			$ts = $this->translateThread($thread);
+			$apiPage['threads'][] = current($ts['posts']);
+		}
+		return $apiPage;
+	}
+
+	function translateCatalog($catalog) {
+		$apiCatalog = array();
+		foreach ($catalog as $page => $threads) {
+			$apiPage = $this->translateCatalogPage($threads);
+			$apiPage['page'] = $page;
+			$apiCatalog[] = $apiPage;
+		}
+
+		return $apiCatalog;
+	}
+}
diff --git a/inc/functions.php b/inc/functions.php
index d5348f0d..cedf5534 100644
--- a/inc/functions.php
+++ b/inc/functions.php
@@ -13,6 +13,7 @@ require_once 'inc/display.php';
 require_once 'inc/template.php';
 require_once 'inc/database.php';
 require_once 'inc/events.php';
+require_once 'inc/api.php';
 require_once 'inc/lib/gettext/gettext.inc';
 
 // the user is not currently logged in as a moderator
@@ -1047,6 +1048,9 @@ function index($page, $mod=false) {
 
 	if ($query->rowCount() < 1 && $page > 1)
 		return false;
+
+	$threads = array();
+	
 	while ($th = $query->fetch(PDO::FETCH_ASSOC)) {
 		$thread = new Thread($th, $mod ? '?/' : $config['root'], $mod);
 
@@ -1087,7 +1091,8 @@ function index($page, $mod=false) {
 			$thread->omitted = $omitted['post_count'] - ($th['sticky'] ? $config['threads_preview_sticky'] : $config['threads_preview']);
 			$thread->omitted_images = $omitted['image_count'] - $num_images;
 		}
-
+		
+		$threads[] = $thread;
 		$body .= $thread->build(true);
 	}
 
@@ -1096,7 +1101,8 @@ function index($page, $mod=false) {
 		'body' => $body,
 		'post_url' => $config['post_url'],
 		'config' => $config,
-		'boardlist' => createBoardlist($mod)
+		'boardlist' => createBoardlist($mod),
+		'threads' => $threads
 	);
 }
 
@@ -1289,10 +1295,14 @@ function buildIndex() {
 	if (!$config['try_smarter'])
 		$antibot = create_antibot($board['uri']);
 
+	$api = new Api();
+	$catalog = array();
+	
 	for ($page = 1; $page <= $config['max_pages']; $page++) {
 		$filename = $board['dir'] . ($page == 1 ? $config['file_index'] : sprintf($config['file_page'], $page));
 
-		if ($config['try_smarter'] && isset($build_pages) && count($build_pages) && !in_array($page, $build_pages) && is_file($filename))
+		if ($config['try_smarter'] && isset($build_pages) && count($build_pages)
+			&& !in_array($page, $build_pages) && is_file($filename))
 			continue;
 		$content = index($page);
 		if (!$content)
@@ -1309,13 +1319,30 @@ function buildIndex() {
 		$content['antibot'] = $antibot;
 
 		file_write($filename, Element('index.html', $content));
+		
+		// json api
+		$threads = $content['threads'];
+		$json = json_encode($api->translatePage($threads));
+		$jsonFilename = $board['dir'] . ($page-1) . ".json"; // pages should start from 0
+		file_write($jsonFilename, $json);
+
+		$catalog[$page-1] = $threads;
 	}
+
 	if ($page < $config['max_pages']) {
 		for (;$page<=$config['max_pages'];$page++) {
 			$filename = $board['dir'] . ($page==1 ? $config['file_index'] : sprintf($config['file_page'], $page));
 			file_unlink($filename);
+
+			$jsonFilename = $board['dir'] . ($page-1) . ".json";
+			file_unlink($jsonFilename);
 		}
 	}
+
+	// json api catalog
+	$json = json_encode($api->translateCatalog($catalog));
+	$jsonFilename = $board['dir'] . "catalog.json";
+	file_write($jsonFilename, $json);
 }
 
 function buildJavascript() {
@@ -1735,6 +1762,12 @@ function buildThread($id, $return = false, $mod = false) {
 		return $body;
 
 	file_write($board['dir'] . $config['dir']['res'] . sprintf($config['file_page'], $id), $body);
+
+	// json api
+	$api = new Api();
+	$json = json_encode($api->translateThread($thread));
+	$jsonFilename = $board['dir'] . $config['dir']['res'] . $id . ".json";
+	file_write($jsonFilename, $json);
 }
 
  function rrmdir($dir) {