diff --git a/src/Exception/AuthConfigException.php b/src/Exception/AuthConfigException.php
new file mode 100644
index 0000000..2ee3bed
--- /dev/null
+++ b/src/Exception/AuthConfigException.php
@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace tr33m4n\OauthGmail\Exception;
+
+use Magento\Framework\Exception\LocalizedException;
+
+class AuthConfigException extends LocalizedException
+{
+    //
+}
diff --git a/src/Model/Client/ConfigureAuthConfig.php b/src/Model/Client/ConfigureAuthConfig.php
index fd10c2c..3995cd4 100644
--- a/src/Model/Client/ConfigureAuthConfig.php
+++ b/src/Model/Client/ConfigureAuthConfig.php
@@ -1,4 +1,5 @@
 <?php
+
 declare(strict_types=1);
 
 namespace tr33m4n\OauthGmail\Model\Client;
@@ -6,9 +7,18 @@
 use Google\Client;
 use Magento\Backend\Model\UrlInterface;
 use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\App\Filesystem\DirectoryList;
+use Magento\Framework\Filesystem;
+use Magento\Framework\Filesystem\Directory\ReadInterface;
+use tr33m4n\OauthGmail\Exception\AuthConfigException;
+use tr33m4n\OauthGmail\Model\Config\Source\AuthType;
 
 class ConfigureAuthConfig
 {
+    private const XML_CONFIG_AUTH_TYPE = 'system/oauth_gmail/auth_type';
+
+    private const XML_CONFIG_AUTH_FILE = 'system/oauth_gmail/auth_file';
+
     private const XML_CONFIG_CLIENT_ID_PATH = 'system/oauth_gmail/client_id';
 
     private const XML_CONFIG_CLIENT_SECRET_PATH = 'system/oauth_gmail/client_secret';
@@ -17,36 +27,59 @@ class ConfigureAuthConfig
 
     private UrlInterface $url;
 
+    private ReadInterface $varDirectory;
+
     /**
      * ConfigureAuthConfig constructor.
      *
      * @param \Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig
+     * @param \Magento\Framework\Filesystem                      $filesystem
      * @param \Magento\Backend\Model\UrlInterface                $url
      */
     public function __construct(
         ScopeConfigInterface $scopeConfig,
+        Filesystem $filesystem,
         UrlInterface $url
     ) {
         $this->scopeConfig = $scopeConfig;
         $this->url = $url;
+        $this->varDirectory = $filesystem->getDirectoryRead(DirectoryList::VAR_DIR);
     }
 
     /**
      * Configure auth config
      *
      * @throws \Google\Exception
+     * @throws \tr33m4n\OauthGmail\Exception\AuthConfigException
      * @param \Google\Client $client
      * @return \Google\Client
      */
-    public function execute(Client $client) : Client
+    public function execute(Client $client): Client
     {
-        $client->setAuthConfig([
-            'client_id' => $this->scopeConfig->getValue(self::XML_CONFIG_CLIENT_ID_PATH),
-            'client_secret' => $this->scopeConfig->getValue(self::XML_CONFIG_CLIENT_SECRET_PATH),
-            'redirect_uris' => [
-                $this->getRedirectUrl()
-            ]
-        ]);
+        switch ($this->scopeConfig->getValue(self::XML_CONFIG_AUTH_TYPE)) {
+            case AuthType::AUTH_TYPE_FILE:
+                $authFile = $this->varDirectory->getAbsolutePath(
+                    $this->scopeConfig->getValue(self::XML_CONFIG_AUTH_FILE)
+                );
+
+                if (!$this->varDirectory->isExist($authFile)) {
+                    throw new AuthConfigException(__('Auth file does not exist'));
+                }
+
+                $client->setAuthConfig($authFile);
+                break;
+            case AuthType::AUTH_TYPE_CLIENT_ID_SECRET:
+                $client->setAuthConfig([
+                    'client_id' => $this->scopeConfig->getValue(self::XML_CONFIG_CLIENT_ID_PATH),
+                    'client_secret' => $this->scopeConfig->getValue(self::XML_CONFIG_CLIENT_SECRET_PATH),
+                    'redirect_uris' => [
+                        $this->getRedirectUrl()
+                    ]
+                ]);
+                break;
+            default:
+                throw new AuthConfigException(__('Invalid auth type'));
+        }
 
         return $client;
     }
@@ -56,7 +89,7 @@ public function execute(Client $client) : Client
      *
      * @return string
      */
-    private function getRedirectUrl() : string
+    private function getRedirectUrl(): string
     {
         $this->url->turnOffSecretKey();
         $callbackUrl = $this->url->getUrl('oauthgmail/callback/authenticate');
diff --git a/src/Model/Config/Backend/AuthFile.php b/src/Model/Config/Backend/AuthFile.php
new file mode 100644
index 0000000..b49b419
--- /dev/null
+++ b/src/Model/Config/Backend/AuthFile.php
@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+namespace tr33m4n\OauthGmail\Model\Config\Backend;
+
+use Magento\Config\Model\Config\Backend\File;
+use Magento\Framework\App\Cache\TypeListInterface;
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\App\Filesystem\DirectoryList;
+use Magento\Framework\Data\Collection\AbstractDb;
+use Magento\Framework\Filesystem;
+use Magento\Framework\Model\Context;
+use Magento\Framework\Model\ResourceModel\AbstractResource;
+use Magento\Framework\Registry;
+use Magento\MediaStorage\Model\File\UploaderFactory;
+
+class AuthFile extends File
+{
+    /**
+     * AuthFile constructor.
+     *
+     * @throws \Magento\Framework\Exception\FileSystemException
+     * @param \Magento\Framework\Model\Context                                           $context
+     * @param \Magento\Framework\Registry                                                $registry
+     * @param \Magento\Framework\App\Config\ScopeConfigInterface                         $config
+     * @param \Magento\Framework\App\Cache\TypeListInterface                             $cacheTypeList
+     * @param \Magento\MediaStorage\Model\File\UploaderFactory                           $uploaderFactory
+     * @param \Magento\Config\Model\Config\Backend\File\RequestData\RequestDataInterface $requestData
+     * @param \Magento\Framework\Filesystem                                              $filesystem
+     * @param \Magento\Framework\Model\ResourceModel\AbstractResource|null               $resource
+     * @param \Magento\Framework\Data\Collection\AbstractDb|null                         $resourceCollection
+     * @param array<string, mixed>                                                       $data
+     */
+    public function __construct(
+        Context $context,
+        Registry $registry,
+        ScopeConfigInterface $config,
+        TypeListInterface $cacheTypeList,
+        UploaderFactory $uploaderFactory,
+        File\RequestData\RequestDataInterface $requestData,
+        Filesystem $filesystem, AbstractResource $resource = null,
+        AbstractDb $resourceCollection = null,
+        array $data = []
+    ) {
+        // Ensure we do not save the auth JSON file in a public location
+        $this->_mediaDirectory = $filesystem->getDirectoryWrite(DirectoryList::VAR_DIR);
+
+        parent::__construct(
+            $context,
+            $registry,
+            $config,
+            $cacheTypeList,
+            $uploaderFactory,
+            $requestData,
+            $filesystem,
+            $resource,
+            $resourceCollection,
+            $data
+        );
+    }
+
+    /**
+     * @inheritDoc
+     */
+    protected function _getAllowedExtensions(): array
+    {
+        return ['json'];
+    }
+}
diff --git a/src/Model/Config/Source/AuthType.php b/src/Model/Config/Source/AuthType.php
new file mode 100644
index 0000000..a7faa3c
--- /dev/null
+++ b/src/Model/Config/Source/AuthType.php
@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace tr33m4n\OauthGmail\Model\Config\Source;
+
+use Magento\Framework\Data\OptionSourceInterface;
+
+class AuthType implements OptionSourceInterface
+{
+    public const AUTH_TYPE_FILE = 'file';
+
+    public const AUTH_TYPE_CLIENT_ID_SECRET = 'client_id_secret';
+
+    /**
+     * {@inheritdoc}
+     *
+     * @return array[]
+     */
+    public function toOptionArray(): array
+    {
+        return [
+            ['label' => __('Client ID/Secret'), 'value' => self::AUTH_TYPE_CLIENT_ID_SECRET],
+            ['label' => __('File'), 'value' => self::AUTH_TYPE_FILE]
+        ];
+    }
+}
diff --git a/src/etc/adminhtml/system.xml b/src/etc/adminhtml/system.xml
index a0b3218..5da4be3 100644
--- a/src/etc/adminhtml/system.xml
+++ b/src/etc/adminhtml/system.xml
@@ -6,19 +6,39 @@
             <group id="oauth_gmail" translate="label" type="text" sortOrder="1" showInDefault="1"
                    showInWebsite="0" showInStore="0">
                 <label>Oauth Gmail</label>
-                <field id="client_id" translate="label" type="text" sortOrder="1" showInDefault="1"
+                <field id="auth_type" translate="label" type="select" sortOrder="1" showInDefault="1" showInWebsite="0"
+                       showInStore="0">
+                    <label>Auth Type</label>
+                    <source_model>tr33m4n\OauthGmail\Model\Config\Source\AuthType</source_model>
+                </field>
+                <field id="auth_file" translate="label" type="file" sortOrder="2" showInDefault="1" showInWebsite="0"
+                       showInStore="0">
+                    <label>Auth File</label>
+                    <backend_model>tr33m4n\OauthGmail\Model\Config\Backend\AuthFile</backend_model>
+                    <upload_dir config="system" scope_info="1">oauth_gmail</upload_dir>
+                    <depends>
+                        <field id="system/oauth_gmail/auth_type">file</field>
+                    </depends>
+                </field>
+                <field id="client_id" translate="label" type="text" sortOrder="3" showInDefault="1"
                        showInWebsite="0" showInStore="0">
                     <label>Client ID</label>
+                    <depends>
+                        <field id="system/oauth_gmail/auth_type">client_id_secret</field>
+                    </depends>
                 </field>
-                <field id="client_secret" translate="label" type="obscure" sortOrder="2" showInDefault="1"
+                <field id="client_secret" translate="label" type="obscure" sortOrder="4" showInDefault="1"
                        showInWebsite="0" showInStore="0">
                     <label>Client Secret</label>
                     <backend_model>Magento\Config\Model\Config\Backend\Encrypted</backend_model>
+                    <depends>
+                        <field id="system/oauth_gmail/auth_type">client_id_secret</field>
+                    </depends>
                 </field>
-                <field id="authenticate" sortOrder="3" showInDefault="1" showInWebsite="0" showInStore="0">
+                <field id="authenticate" sortOrder="5" showInDefault="1" showInWebsite="0" showInStore="0">
                     <frontend_model>tr33m4n\OauthGmail\Block\Adminhtml\System\Config\Authenticate</frontend_model>
                 </field>
-                <field id="send_test" sortOrder="3" showInDefault="1" showInWebsite="0" showInStore="0">
+                <field id="send_test" sortOrder="6" showInDefault="1" showInWebsite="0" showInStore="0">
                     <frontend_model>tr33m4n\OauthGmail\Block\Adminhtml\System\Config\SendTest</frontend_model>
                 </field>
             </group>
diff --git a/src/etc/config.xml b/src/etc/config.xml
index de40688..06c7d52 100644
--- a/src/etc/config.xml
+++ b/src/etc/config.xml
@@ -5,6 +5,7 @@
         <system>
             <oauth_gmail>
                 <client_secret backend_model="Magento\Config\Model\Config\Backend\Encrypted"/>
+                <auth_type>client_id_secret</auth_type>
             </oauth_gmail>
         </system>
     </default>