diff --git a/api/index.php b/api/index.php
index 8e85919c6629df0cfa07f1a0943cd507f119e1a7..77552af4605d3577fdde85e1e33e442deb60ef80 100644
--- a/api/index.php
+++ b/api/index.php
@@ -41,11 +41,11 @@
 		}
 	} else {
 		// Accept JSON only
-		$input = json_decode($input, true);
+		$input = json_decode((string)$input, true);
 		$_REQUEST = $input;
 	}
 
-	if ($_REQUEST["sid"]) {
+	if (!empty($_REQUEST["sid"])) {
 		session_id($_REQUEST["sid"]);
 		@session_start();
 	} else if (defined('_API_DEBUG_HTTP_ENABLED')) {
@@ -56,7 +56,7 @@
 
 	if (!init_plugins()) return;
 
-	if ($_SESSION["uid"]) {
+	if (!empty($_SESSION["uid"])) {
 		if (!validate_session()) {
 			header("Content-Type: text/json");
 
@@ -67,7 +67,7 @@
 			return;
 		}
 
-		UserHelper::load_user_plugins( $_SESSION["uid"]);
+		UserHelper::load_user_plugins($_SESSION["uid"]);
 	}
 
 	$method = strtolower($_REQUEST["op"]);
@@ -77,7 +77,7 @@
 	if ($handler->before($method)) {
 		if ($method && method_exists($handler, $method)) {
 			$handler->$method();
-		} else if (method_exists($handler, 'index')) {
+		} else /* if (method_exists($handler, 'index')) */ {
 			$handler->index($method);
 		}
 		$handler->after();
diff --git a/classes/api.php b/classes/api.php
index 4dd92be8870ce5665510adaa2a3d16bf93a7549f..2f07e9ead6fea3bcfe1c472fb514895caab0989f 100755
--- a/classes/api.php
+++ b/classes/api.php
@@ -16,12 +16,12 @@ class API extends Handler {
 		if (parent::before($method)) {
 			header("Content-Type: text/json");
 
-			if (!$_SESSION["uid"] && $method != "login" && $method != "isloggedin") {
+			if (empty($_SESSION["uid"]) && $method != "login" && $method != "isloggedin") {
 				$this->wrap(self::STATUS_ERR, array("error" => 'NOT_LOGGED_IN'));
 				return false;
 			}
 
-			if ($_SESSION["uid"] && $method != "logout" && !get_pref('ENABLE_API_ACCESS')) {
+			if (!empty($_SESSION["uid"]) && $method != "logout" && !get_pref('ENABLE_API_ACCESS')) {
 				$this->wrap(self::STATUS_ERR, array("error" => 'API_DISABLED'));
 				return false;
 			}
@@ -120,7 +120,7 @@ class API extends Handler {
 		$unread_only = self::param_to_bool(clean($_REQUEST["unread_only"] ?? 0));
 		$limit = (int) clean($_REQUEST["limit"] ?? 0);
 		$offset = (int) clean($_REQUEST["offset"] ?? 0);
-		$include_nested = self::param_to_bool(clean($_REQUEST["include_nested"]));
+		$include_nested = self::param_to_bool(clean($_REQUEST["include_nested"] ?? false));
 
 		$feeds = $this->api_get_feeds($cat_id, $unread_only, $limit, $offset, $include_nested);
 
@@ -128,9 +128,9 @@ class API extends Handler {
 	}
 
 	function getCategories() {
-		$unread_only = self::param_to_bool(clean($_REQUEST["unread_only"]));
-		$enable_nested = self::param_to_bool(clean($_REQUEST["enable_nested"]));
-		$include_empty = self::param_to_bool(clean($_REQUEST['include_empty']));
+		$unread_only = self::param_to_bool(clean($_REQUEST["unread_only"] ?? false));
+		$enable_nested = self::param_to_bool(clean($_REQUEST["enable_nested"] ?? false));
+		$include_empty = self::param_to_bool(clean($_REQUEST['include_empty'] ?? false));
 
 		// TODO do not return empty categories, return Uncategorized and standard virtual cats
 
@@ -195,7 +195,7 @@ class API extends Handler {
 			if (!$limit || $limit >= 200) $limit = 200;
 
 			$offset = (int)clean($_REQUEST["skip"]);
-			$filter = clean($_REQUEST["filter"]);
+			$filter = clean($_REQUEST["filter"] ?? "");
 			$is_cat = self::param_to_bool(clean($_REQUEST["is_cat"]));
 			$show_excerpt = self::param_to_bool(clean($_REQUEST["show_excerpt"]));
 			$show_content = self::param_to_bool(clean($_REQUEST["show_content"]));
@@ -206,11 +206,11 @@ class API extends Handler {
 			$include_nested = self::param_to_bool(clean($_REQUEST["include_nested"]));
 			$sanitize_content = !isset($_REQUEST["sanitize"]) ||
 				self::param_to_bool($_REQUEST["sanitize"]);
-			$force_update = self::param_to_bool(clean($_REQUEST["force_update"]));
-			$has_sandbox = self::param_to_bool(clean($_REQUEST["has_sandbox"]));
-			$excerpt_length = (int)clean($_REQUEST["excerpt_length"]);
-			$check_first_id = (int)clean($_REQUEST["check_first_id"]);
-			$include_header = self::param_to_bool(clean($_REQUEST["include_header"]));
+			$force_update = self::param_to_bool(clean($_REQUEST["force_update"] ?? false));
+			$has_sandbox = self::param_to_bool(clean($_REQUEST["has_sandbox"] ?? false));
+			$excerpt_length = (int)clean($_REQUEST["excerpt_length"] ?? 0);
+			$check_first_id = (int)clean($_REQUEST["check_first_id"] ?? 0);
+			$include_header = self::param_to_bool(clean($_REQUEST["include_header"] ?? false));
 
 			$_SESSION['hasSandbox'] = $has_sandbox;
 
@@ -218,7 +218,7 @@ class API extends Handler {
 
 			/* do not rely on params below */
 
-			$search = clean($_REQUEST["search"]);
+			$search = clean($_REQUEST["search"] ?? "");
 
 			list($headlines, $headlines_header) = $this->api_get_headlines($feed_id, $limit, $offset,
 				$filter, $is_cat, $show_excerpt, $show_content, $view_mode, $override_order,