diff --git a/get_credential.php b/get_credential.php
index 0de76a53..b928197a 100644
--- a/get_credential.php
+++ b/get_credential.php
@@ -1,11 +1,27 @@
 <?php
 
+/*
+ * ITFlow browser extension
+ *
+ * Fills login forms, matching on the site URL:
+ * After installation and configuration of the extension, users can simply click the key to fill the form on the page
+ * If the URL of the page matches a configured login URL in ITFlow, the username and password is filled.
+ *
+ * Technical details:-
+ * First, review how ITFlow handles password encryption: https://itflow.org/docs.php?doc=logins
+ * Users must enable the extension via their profile/settings.
+ * An extension key is generated and stored in the users table, and provided to the user as a cookie every time they log in. Additionally, their PHP Session ID is also stored in the users table.
+ * The extension passes this cookie on all requests it makes (to this page). We use the cookie/key to identify/verify the user.
+ * We can then access the users PHP session data. This, alongside the user_encryption_session_key cookie they provide, allows login passwords to be decrypted.
+ *
+ */
+
 // Headers to allow extensions access (CORS)
 $chrome_id = "chrome-extension://afgpakhonllnmnomchjhidealcpmnegc";
-$firefox_id = "moz-extension://857479e9-3992-4e99-9a5e-b514d2ad0a82";
+//$firefox_id = "moz-extension://857479e9-3992-4e99-9a5e-b514d2ad0a82"; // Firefox rejected the extension. They are still using manifest v2 so will just focus on Chrome/Edge with v3 for now until Mozilla catches up
 
 if (isset($_SERVER['HTTP_ORIGIN'])) {
-    if($_SERVER['HTTP_ORIGIN'] == $chrome_id || $_SERVER['HTTP_ORIGIN'] == $firefox_id){
+    if($_SERVER['HTTP_ORIGIN'] == $chrome_id){
         header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
         header('Access-Control-Allow-Credentials: true');
     }
@@ -14,21 +30,24 @@ if (isset($_SERVER['HTTP_ORIGIN'])) {
 include("config.php");
 include("functions.php");
 
-//SESSION FINGERPRINT
+// IP & User Agent for logging
 $ip = strip_tags(mysqli_real_escape_string($mysqli,get_ip()));
-$os = strip_tags(mysqli_real_escape_string($mysqli,get_os()));
-$browser = strip_tags(mysqli_real_escape_string($mysqli,get_web_browser()));
-$user_agent = "$os - $browser";
+$user_agent = strip_tags(mysqli_real_escape_string($mysqli,$_SERVER['HTTP_USER_AGENT']));
+
+// Define wording for the user
+DEFINE("WORDING_ROLECHECK_FAILED", "ITFlow - You are not permitted to use this application!");
+DEFINE("WORDING_BAD_EXT_COOKIE_KEY", "ITFlow - You are not logged into ITFlow, do not have, or did not send the correct extension key cookie.");
+
 
 // Check user is logged in & has extension access
 // We're not using the PHP session as we don't want to potentially expose the session cookie with SameSite None
 if(!isset($_COOKIE['user_extension_key'])){
     $data['found'] = "FALSE";
-    $data['message'] = "ITFlow - You are not logged into ITFlow, do not have, or did not send the correct extension key cookie.";
+    $data['message'] = WORDING_BAD_EXT_COOKIE_KEY;
     echo(json_encode($data));
 
     //Logging
-    mysqli_query($mysqli,"INSERT INTO logs SET log_type = 'Login', log_action = 'Extension Failed', log_description = 'Failed login attempt using extension (get_credential.php)', log_ip = '$ip', log_user_agent = '$user_agent', log_created_at = NOW()");
+    mysqli_query($mysqli,"INSERT INTO logs SET log_type = 'Login', log_action = 'Extension Failed', log_description = 'Failed login attempt using extension (get_credential.php)', log_ip = '$ip', log_user_agent = '$user_agent'");
 
     exit();
 }
@@ -39,11 +58,11 @@ $user_extension_key = $_COOKIE['user_extension_key'];
 // Check the key isn't empty, less than 17 characters or the word "disabled".
 if(empty($user_extension_key) || strlen($user_extension_key) < 16 || strtolower($user_extension_key) == "disabled"){
     $data['found'] = "FALSE";
-    $data['message'] = "ITFlow - You are not logged into ITFlow, do not have, or did not send the correct extension key cookie.";
+    $data['message'] = WORDING_BAD_EXT_COOKIE_KEY;
     echo(json_encode($data));
 
     //Logging
-    mysqli_query($mysqli,"INSERT INTO logs SET log_type = 'Login', log_action = 'Extension Failed', log_description = 'Failed login attempt using extension (get_credential.php)', log_ip = '$ip', log_user_agent = '$user_agent', log_created_at = NOW()");
+    mysqli_query($mysqli,"INSERT INTO logs SET log_type = 'Login', log_action = 'Extension Failed', log_description = 'Failed login attempt using extension (get_credential.php)', log_ip = '$ip', log_user_agent = '$user_agent'");
 
     exit();
 }
@@ -57,11 +76,11 @@ $row = mysqli_fetch_array($auth_user);
 // Check SQL query state
 if(mysqli_num_rows($auth_user) < 1 || !$auth_user){
     $data['found'] = "FALSE";
-    $data['message'] = "ITFlow - You are not logged into ITFlow, do not have, or did not send the correct extension key cookie.";
+    $data['message'] = WORDING_BAD_EXT_COOKIE_KEY;
     echo(json_encode($data));
 
     //Logging
-    mysqli_query($mysqli,"INSERT INTO logs SET log_type = 'Login', log_action = 'Extension Failed', log_description = 'Failed login attempt using extension (get_credential.php)', log_ip = '$ip', log_user_agent = '$user_agent', log_created_at = NOW()");
+    mysqli_query($mysqli,"INSERT INTO logs SET log_type = 'Login', log_action = 'Extension Failed', log_description = 'Failed login attempt using extension (get_credential.php)', log_ip = '$ip', log_user_agent = '$user_agent'");
 
     exit();
 }
@@ -69,51 +88,36 @@ if(mysqli_num_rows($auth_user) < 1 || !$auth_user){
 // Sanity check
 if(hash('sha256', $row['user_extension_key']) !== hash('sha256', $_COOKIE['user_extension_key'])){
     $data['found'] = "FALSE";
-    $data['message'] = "ITFlow - Validation failed.";
+    $data['message'] = WORDING_BAD_EXT_COOKIE_KEY;
     echo(json_encode($data));
 
     //Logging
-    mysqli_query($mysqli,"INSERT INTO logs SET log_type = 'Login', log_action = 'Extension Failed', log_description = 'Failed login attempt using extension (get_credential.php)', log_ip = '$ip', log_user_agent = '$user_agent', log_created_at = NOW()");
+    mysqli_query($mysqli,"INSERT INTO logs SET log_type = 'Login', log_action = 'Extension Failed', log_description = 'Failed login attempt using extension (get_credential.php)', log_ip = '$ip', log_user_agent = '$user_agent'");
 
     exit();
 }
 
 // Success - validated user cookie
 
-// Get the current session from the database so we can decrypt passwords
+// Get the current session from the database, so we can decrypt passwords
 session_id($row['user_php_session']);
 session_start();
 
 $session_user_id = $row['user_id'];
 $session_name = $row['user_name'];
 $session_email = $row['user_email'];
-$session_avatar = $row['user_avatar'];
-$session_token = $row['user_token'];
 $session_company_id = $row['user_default_company'];
 $session_user_role = $row['user_role'];
-if($session_user_role == 6){
-    $session_user_role_display = "Global Administrator";
-}elseif($session_user_role == 5){
-    $session_user_role_display = "Administrator";
-}elseif($session_user_role == 4){
-    $session_user_role_display = "Technician";
-}elseif($session_user_role == 3){
-    $session_user_role_display = "IT Contractor";
-}elseif($session_user_role == 2){
-    $session_user_role_display = "Client";
-}else{
-    $session_user_role_display = "Accountant";
-}
 
-// Check user access level is correct
-if($session_user_role < 4){
+// Check user access level is correct (not an accountant)
+if($session_user_role < 1){
     $data['found'] = "FALSE";
-    $data['message'] = "ITFlow - You are not authorised to use this application.";
+    $data['message'] = WORDING_ROLECHECK_FAILED;
     echo(json_encode($data));
 
     //Logging
     $user_name = mysqli_real_escape_string($mysqli, $session_name);
-    mysqli_query($mysqli,"INSERT INTO logs SET log_type = 'Login', log_action = 'Extension Failed', log_description = '$user_name not authorised to use extension', log_ip = '$ip', log_user_agent = '$user_agent', log_created_at = NOW(), log_user_id = $session_user_id");
+    mysqli_query($mysqli,"INSERT INTO logs SET log_type = 'Login', log_action = 'Extension Failed', log_description = '$user_name not authorised to use extension', log_ip = '$ip', log_user_agent = '$user_agent', log_user_id = $session_user_id");
 
     exit();
 }
@@ -131,18 +135,17 @@ if(isset($_GET['host'])){
             $row = mysqli_fetch_array($sql_logins);
             $data['found'] = "TRUE";
             $data['username'] = htmlentities($row['login_username']);
-            $data['password'] = decryptLoginEntry($row['login_password']);
+            $data['password'] = decryptLoginEntry($row['login_password']); // Uses the PHP Session info and the session key cookie
             echo json_encode($data);
 
             // Logging
             $login_name = mysqli_real_escape_string($mysqli, $row['login_name']);
             $login_user = mysqli_real_escape_string($mysqli, $row['login_username']);
-            mysqli_query($mysqli, "INSERT INTO logs SET log_type = 'Login', log_action = 'Extension requested', log_description = 'Credential $login_name, username $login_user', log_ip = '$ip', log_user_agent = '$user_agent', log_created_at = NOW(), company_id = $session_company_id, log_user_id = $session_user_id");
+            mysqli_query($mysqli, "INSERT INTO logs SET log_type = 'Login', log_action = 'Extension requested', log_description = 'Credential $login_name, username $login_user', log_ip = '$ip', log_user_agent = '$user_agent', company_id = $session_company_id, log_user_id = $session_user_id");
 
         }
     }
 }
 
 //TODO: Future work:-
-// - Check user has permission to this client
 // - Showing multiple logins for a single URL
\ No newline at end of file