diff --git a/backend/Db.php b/backend/Db.php
index 008e20a..babbaab 100644
--- a/backend/Db.php
+++ b/backend/Db.php
@@ -1,11 +1,16 @@
 <?php
 class Db {
   private $dbh;
-  function _construct() {
+  function __construct() {
     $this->dbh = new PDO('mysql:host=localhost;dbname=lexiconga;charset=utf8', 'root', 'password');
     $this->dbh->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
   }
 
+  public function execute ($query, $params = array()) {
+    $stmt = $this->dbh->prepare($query);
+    return $stmt->execute($params);
+  }
+
   public function query ($query, $params = array()) {
     $stmt = $this->dbh->prepare($query);
     $stmt->execute($params);
diff --git a/backend/Response.php b/backend/Response.php
index 28ed296..7f9986f 100644
--- a/backend/Response.php
+++ b/backend/Response.php
@@ -1,8 +1,14 @@
 <?php
 class Response {
-  public static function out ($data, $http_code) {
-    header('Content-Type: application/json');
+  public static function json ($data, $http_code = 200) {
+    header('Content-Type: application/json; charset=utf-8');
     http_response_code($http_code);
     echo json_encode($data);
+  }
+
+  public static function html ($html, $http_code = 200) {
+    header('Content-Type: text/html; charset=utf-8');
+    http_response_code($http_code);
+    echo $html;
 	}
 }
\ No newline at end of file
diff --git a/backend/Token.php b/backend/Token.php
index 2bfcb02..b55bb1a 100644
--- a/backend/Token.php
+++ b/backend/Token.php
@@ -4,7 +4,7 @@ use \Firebase\JWT\JWT;
 
 class Token {
   private $key;
-  function _construct() {
+  function __construct() {
     $this->key = 'ˈkɑːn.læŋ.ɪŋ_4eva';
   }
 
diff --git a/backend/User.php b/backend/User.php
index 18afd73..59fcdf7 100644
--- a/backend/User.php
+++ b/backend/User.php
@@ -1,11 +1,11 @@
 <?php
-require_once('./Db');
-require_once('./Token');
+require_once('./Db.php');
+require_once('./Token.php');
 
 class User {
   private $db;
   private $token;
-  function _construct () {
+  function __construct () {
     $this->db = new Db();
     $this->token = new Token();
   }
@@ -32,63 +32,58 @@ class User {
     return false;
   }
 
+  public function emailExists ($email) {
+    $query = 'SELECT * FROM users WHERE email=?';
+    $user = $this->db->query($query, array($email));
+    return $user->rowCount() > 0;
+  }
+
   public function create ($email, $password) {
     $insert_user_query = 'INSERT INTO users (email, password) VALUES (?, ?)';
     $password_hash = password_hash($password, PASSWORD_DEFAULT);
 
-    // Use a transaction to make sure all pieces are created successfully.
-    $this->db->dbh->beginTransaction();
-
-    $insert_user = $this->db->query($insert_user_query, array($email, $password_hash));
+    $insert_user = $this->db->execute($insert_user_query, array($email, $password_hash));
     if ($insert_user === true) {
       $new_user_id = $this->db->lastInsertId();
 
       $token = $this->createDictionary($new_user_id);
 
       if ($token !== false) {
-        if ($this->db->dbh->commit()) {
-          return $token;
-        }
+        return $token;
       }
     }
 
-    $this->db->dbh->rollBack();
     return false;
   }
 
   public function createDictionary ($user) {
-    $this->db->dbh->beginTransaction();
-
     $insert_dictionary_query = "INSERT INTO dictionaries (user) VALUES ($user)";
-    $insert_dictionary = $this->db->query($insert_dictionary_query);
+    $insert_dictionary = $this->db->execute($insert_dictionary_query);
 
     if ($insert_dictionary === true) {
       $new_dictionary_id = $this->db->lastInsertId();
 
       $insert_linguistics_query = "INSERT INTO dictionary_linguistics (dictionary) VALUES ($new_dictionary_id)";
-      $insert_linguistics = $this->db->query($insert_dictionary_query);
+      $insert_linguistics = $this->db->execute($insert_linguistics_query);
 
       if ($insert_linguistics === true) {
         if ($this->changeCurrentDictionary($user, $new_dictionary_id)) {
-          if ($this->db->dbh->commit()) {
-            $user_data = array(
-              'id' => $user,
-              'isMember' => $this->hasMembership($user['id']),
-              'dictionary' => $new_dictionary_id,
-            );
-            return $this->token->encode($user_data);
-          }
+          $user_data = array(
+            'id' => $user,
+            'isMember' => $this->hasMembership($user),
+            'dictionary' => $new_dictionary_id,
+          );
+          return $this->token->encode($user_data);
         }
       }
     }
 
-    $this->db->dbh->rollBack();
     return false;
   }
 
   public function changeCurrentDictionary ($user, $dictionary) {
     $update_query = 'UPDATE users SET current_dictionary=? WHERE id=?';
-    $update = $this->db->query($update_query, array($user, $dictionary));
+    $update = $this->db->query($update_query, array($dictionary, $user));
     if ($update->rowCount() > 0) {
       return true;
     }
diff --git a/backend/index.php b/backend/index.php
index bcf96e0..5a3c841 100644
--- a/backend/index.php
+++ b/backend/index.php
@@ -2,48 +2,61 @@
 require_once('./Response.php');
 require_once('./User.php');
 
-$action = $_POST['action'];
-$token = $_POST['token'];
+$inputJSON = file_get_contents('php://input');
+$request= json_decode($inputJSON, true);
+
+$action = isset($request['action']) ? $request['action'] : '';
+$token = isset($request['token']) ? $request['token'] : '';
 
 switch ($action) {
   case 'login': {
-    if ($_POST['email'] && $_POST['password']) {
+    if (isset($request['email']) && isset($request['password'])) {
       $user = new User();
-      $token = $user->logIn($_POST['email'], $_POST['password']);
+      $token = $user->logIn($request['email'], $request['password']);
       if ($token !== false) {
-        return Response::out(array(
+        return Response::json(array(
           'data' => $token,
           'error' => false,
         ), 200);
       }
-      return Response::out(array(
+      return Response::json(array(
         'data' => 'Could not log in: incorrect data',
         'error' => true,
-      ), 400);
+      ), 401);
     }
-    return Response::out(array(
+    return Response::json(array(
       'data' => 'Could not log in: required information missing',
       'error' => true,
-    ), 500);
+    ), 400);
   }
   case 'create-account': {
-    if ($_POST['email'] && $_POST['password']) {
+    if (isset($request['email']) && isset($request['password'])) {
       $user = new User();
-      $token = $user->create($_POST['email'], $_POST['password']);
-      if ($token !== false) {
-        return Response::out(array(
-          'data' => $token,
-          'error' => false,
-        ), 200);
+      if (!$user->emailExists($request['email'])) {
+        $token = $user->create($request['email'], $request['password']);
+        if ($token !== false) {
+          return Response::json(array(
+            'data' => $token,
+            'error' => false,
+          ), 201);
+        }
+        return Response::json(array(
+          'data' => 'Could not create account: database error',
+          'error' => true,
+        ), 500);
       }
-      return Response::out(array(
-        'data' => 'Could not create account: incorrect data',
+      return Response::json(array(
+        'data' => 'Could not create account: duplicate email',
         'error' => true,
-      ), 400);
+      ), 403);
     }
-    return Response::out(array(
+    return Response::json(array(
       'data' => 'Could not create account: required information missing',
       'error' => true,
-    ), 500);
+    ), 400);
+  }
+
+  default: {
+    return Response::html('Hi!');
   }
 }
\ No newline at end of file