diff --git a/api/_auth.php b/api/_auth.php
index 531f3cf..24f5fd5 100644
--- a/api/_auth.php
+++ b/api/_auth.php
@@ -4,7 +4,7 @@
 
 
 // Includes
-if ($IS_FRONTEND)
+if (isset($IS_FRONTEND) && $IS_FRONTEND)
 	require_once("api/_db.php");
 else
 	require_once("_db.php");
diff --git a/api/_config.php b/api/_config.php
index 7c94eb5..8161047 100644
--- a/api/_config.php
+++ b/api/_config.php
@@ -35,7 +35,7 @@ function CreateDirIfNotExist ($path) {
 }
 
 // Creating dirs at correct path
-if ($IS_FRONTEND) {
+if (isset($IS_FRONTEND) && $IS_FRONTEND) {
 	CreateDirIfNotExist($Config["media"]["pics_path"]);
 	CreateDirIfNotExist($Config["media"]["prevs_path"]);
 } else {
diff --git a/api/_db.php b/api/_db.php
index 868e429..e4cfee0 100644
--- a/api/_db.php
+++ b/api/_db.php
@@ -4,7 +4,7 @@
 
 
 // Includes
-if ($IS_FRONTEND)
+if (isset($IS_FRONTEND) && $IS_FRONTEND)
 	require_once("api/_config.php");
 else
 	require_once("_config.php");
diff --git a/api/_json.php b/api/_json.php
index 2d4a138..05a847c 100644
--- a/api/_json.php
+++ b/api/_json.php
@@ -4,7 +4,7 @@
 
 
 // Includes
-if ($IS_FRONTEND)
+if (isset($IS_FRONTEND) && $IS_FRONTEND)
 	require_once("api/_errorslist.php");
 else
 	require_once("_errorslist.php");
diff --git a/api/_types.php b/api/_types.php
index 0624b40..4bd43fa 100644
--- a/api/_types.php
+++ b/api/_types.php
@@ -4,7 +4,7 @@
 
 
 // Includes
-if ($IS_FRONTEND) {
+if (isset($IS_FRONTEND) && $IS_FRONTEND) {
 	require_once("api/_errorslist.php");
 	require_once("api/_json.php");
 } else {
diff --git a/api/_utils.php b/api/_utils.php
index fd6b934..93657eb 100644
--- a/api/_utils.php
+++ b/api/_utils.php
@@ -18,7 +18,7 @@ function Utils_GenerateRandomString (int $length, string $keyspace = "abcdefghij
 	for ($i = 0; $i < $length; ++$i) {
 		$pieces []= $keyspace[random_int(0, $max)];
 	}
-	return implode('', $pieces);
+	return implode("", $pieces);
 }
 
 // Get ratio from two values
@@ -37,6 +37,11 @@ function Utils_JoinPaths () {
 	return preg_replace('#/+#','/',join('/', $paths));
 }
 
+// Check if string is valid ASCII
+function Utils_IsAscii (string $str): bool {
+	return (bool)!preg_match("/[\\x80-\\xff]+/", $string);
+}
+
 
 
 ?>
\ No newline at end of file
diff --git a/api/post/create.php b/api/post/create.php
index 5df2add..fe32f33 100644
--- a/api/post/create.php
+++ b/api/post/create.php
@@ -4,18 +4,20 @@
 
 
 // Includes
-if ($IS_FRONTEND) {
+if (isset($IS_FRONTEND) && $IS_FRONTEND) {
 	require_once("api/_auth.php");
 	require_once("api/_utils.php");
 	require_once("api/_errorslist.php");
 	require_once("api/_types.php");
 	require_once("api/user/index.php");
+	require_once("api/tags/index.php");
 } else {
 	require_once("../_auth.php");
 	require_once("../_utils.php");
 	require_once("../_errorslist.php");
 	require_once("../_types.php");
 	require_once("../user/index.php");
+	require_once("../tags/index.php");
 }
 
 
@@ -203,12 +205,20 @@ function Post_Create_Method (array $req, array $files): ReturnT {
 		return new ReturnT(err_code: E_UIN_BADARGS, err_desc: "tags string length exceeds limit: " . strval($Config["posting"]["tags"]["max_raw_input_str_length"]));
 	elseif ($tagsLen < 1)
 		return new ReturnT(err_code: E_UIN_BADARGS, err_desc: "tags cant be empty");
-	// TODO: check if it is ASCII string
+	// Check if supplied string is ASCII
+	if (!Utils_IsAscii($req["tags"]))
+		return new ReturnT(err_code: E_UIN_BADARGS, err_desc: "tags must be ASCII-only");
 	// Parsing tags
 	$parsedTags = Post_ParseRawTagString($req["tags"]);
 	if ($parsedTags->IsError())
 		return $parsedTags;
-	// TODO: check if tags are approved
+	$parsedTags = $parsedTags->GetData();
+	// Check if tags are approved
+	foreach ($parsedTags as $singleTag) {
+		if (!Tags_IsTagApproved($singleTag))
+			return new ReturnT(err_code: E_UIN_BADARGS, err_desc: "tag $singleTag is not approved");
+	}
+	// Concatenating parsed tags to single comma-separated string
 	$tags = implode(",", $parsedTags);
 
 	// Check user role TODO: add rate-limiting, instead of this
diff --git a/api/post/index.php b/api/post/index.php
index 8bb0e3f..4e88f27 100644
--- a/api/post/index.php
+++ b/api/post/index.php
@@ -87,7 +87,7 @@ function Post_GetByID (int $id): ReturnT {
 	$result["edit_lock"]              = $d["edit_lock"];
 
 	$r = Post_AddView($id); // TODO: add rate-limit or completely rework
-	if ($r.IsError())
+	if ($r->IsError())
 		return $r;
 
 	return new ReturnT(data: $result);
diff --git a/api/tags/index.php b/api/tags/index.php
new file mode 100644
index 0000000..1f65376
--- /dev/null
+++ b/api/tags/index.php
@@ -0,0 +1,122 @@
+<?php
+// Get info about tags
+
+
+
+// Includes
+if (isset($IS_FRONTEND) && $IS_FRONTEND) {
+	require_once("api/_auth.php");
+	require_once("api/_utils.php");
+	require_once("api/_errorslist.php");
+	require_once("api/_types.php");
+} else {
+	require_once("../_auth.php");
+	require_once("../_utils.php");
+	require_once("../_errorslist.php");
+	require_once("../_types.php");
+}
+
+
+
+// Functions
+
+/*
+ * FUNCTION
+ * Get list of all approved tags
+ */
+function Tags_GetListOfApproved (): array {
+	global $db;
+
+	$result = array();
+
+	$s = $db->prepare("SELECT * FROM approved_tags ORDER BY value");
+	$s->execute();
+	$d = $s->get_result();
+
+	if (!(bool)$d)
+		return $result;
+
+	while ($row = $d->fetch_array()) {
+		$result[] = $row["value"];
+	}
+
+	return $result;
+}
+
+/*
+ * FUNCTION
+ * Check if tag is in list of approved tags
+ */
+function Tags_IsTagApproved (string $str): bool {
+	global $db;
+
+	$s = $db->prepare("SELECT value FROM approved_tags WHERE value = ?");
+	$s->bind_param("s", $str);
+	$s->execute();
+
+	return (bool)$s->get_result()->fetch_assoc();
+}
+
+
+
+// Methods
+
+/*
+ * METHOD
+ * Check if tag is approved
+ */
+function Tags_IsTagApproved_Method (array $req): ReturnT {
+	global $Config;
+
+	$requestedTag = $req["value"];
+
+	// Input sanity checks
+
+	// Check length
+	$maxTagLen = $Config["posting"]["tags"]["max_single_length"];
+	$realLen = strlen($requestedTag);
+	if ($realLen > $maxTagLen)
+		return new ReturnT(err_code: E_UIN_BADARGS, err_desc: "tag length must be equal to or less than " . strval($maxTagLen));
+	elseif ($realLen < 1)
+		return new ReturnT(err_code: E_UIN_BADARGS, err_desc: "tag can not be empty");
+
+	// Check symbols
+	$allowedSymbols = $Config["posting"]["tags"]["allowed_syms"];
+	$preg_str = "/[^" . $allowedSymbols . "]/";
+	if (preg_match($preg_str, $requestedTag))
+		return new ReturnT(err_code: E_UIN_BADARGS, err_desc: "only allowed symbols in tags are: " . $allowedSymbols);
+
+	// Actions
+
+	return new ReturnT(data: array(
+		"tag" => $requestedTag,
+		"is_approved" => Tags_IsTagApproved($requestedTag)
+	));
+}
+
+/*
+ * METHOD
+ * Get list of all approved tags
+ */
+function Tags_GetListOfApproved_Method (): ReturnT {
+	// Actions
+	return new ReturnT(data: Tags_GetListOfApproved());
+}
+
+
+
+if (Utils_ThisFileIsRequested(__FILE__)) {
+	require_once("../_json.php");
+
+	if (isset($_REQUEST["value"]))
+		$result = Tags_IsTagApproved_Method($_REQUEST);
+	else
+		$result = Tags_GetListOfApproved_Method();
+
+	if ($result->IsError())
+		$result->ThrowJSONError();
+	else
+		JSON_ReturnData($result->GetData());
+}
+
+?>
\ No newline at end of file
diff --git a/api/user/index.php b/api/user/index.php
index a253fea..8aea5ef 100644
--- a/api/user/index.php
+++ b/api/user/index.php
@@ -27,7 +27,7 @@ if ($IS_FRONTEND) {
 function User_LoginExist (string $login): bool {
 	global $db;
 
-	$s = $db->prepare("SELECT * FROM users WHERE login = ?");
+	$s = $db->prepare("SELECT id FROM users WHERE login = ?");
 	$s->bind_param("s", $login);
 	$s->execute();
 
@@ -41,7 +41,7 @@ function User_LoginExist (string $login): bool {
 function User_IDExist (int $id): bool {
 	global $db;
 
-	$s = $db->prepare("SELECT * FROM users WHERE id = ?");
+	$s = $db->prepare("SELECT id FROM users WHERE id = ?");
 	$s->bind_param("s", $id);
 	$s->execute();
 
@@ -55,7 +55,7 @@ function User_IDExist (int $id): bool {
 function User_HasRole (int $id, string $role): ReturnT {
 	global $db;
 
-	$s = $db->prepare("SELECT * FROM users WHERE id = ?");
+	$s = $db->prepare("SELECT role FROM users WHERE id = ?");
 	$s->bind_param("s", $id);
 	$s->execute();
 	$d = $s->get_result()->fetch_assoc();
@@ -73,7 +73,7 @@ function User_HasRole (int $id, string $role): ReturnT {
 function User_IsMod (int $id): ReturnT {
 	global $db;
 
-	$s = $db->prepare("SELECT * FROM users WHERE id = ?");
+	$s = $db->prepare("SELECT role FROM users WHERE id = ?");
 	$s->bind_param("s", $id);
 	$s->execute();
 	$d = $s->get_result()->fetch_assoc();