diff --git a/src/Zulip/Client.php b/src/Zulip/Client.php
index 272301fd..de3362d7 100644
--- a/src/Zulip/Client.php
+++ b/src/Zulip/Client.php
@@ -12,4 +12,20 @@
 
 namespace Guanguans\Notify\Zulip;
 
-class Client extends \Guanguans\Notify\Foundation\Client {}
+use Guanguans\Notify\Foundation\Contracts\Credential;
+
+/**
+ * @see https://chat.zulip.org/accounts/login
+ * @see https://zulip.com/api/send-message
+ */
+class Client extends \Guanguans\Notify\Foundation\Client
+{
+    public function __construct(?Credential $credential = null)
+    {
+        parent::__construct($credential);
+
+        $this->setHttpOptions([
+            'base_uri' => 'https://chat.zulip.org',
+        ]);
+    }
+}
diff --git a/src/Zulip/Credential.php b/src/Zulip/Credential.php
index 775768eb..3ffa7015 100644
--- a/src/Zulip/Credential.php
+++ b/src/Zulip/Credential.php
@@ -16,8 +16,8 @@
 
 class Credential extends BasicAuthCredential
 {
-    public function __construct(string $email, string $token)
+    public function __construct(string $botEmail, string $botApiKey)
     {
-        parent::__construct($email, $token);
+        parent::__construct($botEmail, $botApiKey);
     }
 }
diff --git a/src/Zulip/Messages/DirectMessage.php b/src/Zulip/Messages/DirectMessage.php
new file mode 100644
index 00000000..4a972c50
--- /dev/null
+++ b/src/Zulip/Messages/DirectMessage.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of the guanguans/notify.
+ *
+ * (c) guanguans <ityaozm@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled.
+ */
+
+namespace Guanguans\Notify\Zulip\Messages;
+
+/**
+ * @method \Guanguans\Notify\Zulip\Messages\DirectMessage type($type)
+ * @method \Guanguans\Notify\Zulip\Messages\DirectMessage to($to)
+ * @method \Guanguans\Notify\Zulip\Messages\DirectMessage content($content)
+ */
+class DirectMessage extends Message
+{
+    protected array $defined = [
+        'type',
+        'to',
+        'content',
+    ];
+
+    protected array $required = [
+        'type',
+        'to',
+        'content',
+    ];
+
+    protected array $defaults = [
+        'type' => 'direct',
+    ];
+
+    protected array $allowedTypes = [
+        'to' => ['string', 'int', 'array'],
+    ];
+
+    protected array $allowedValues = [
+        'type' => ['direct'],
+    ];
+
+    protected array $options = [
+        'type' => 'direct',
+    ];
+}
diff --git a/src/Zulip/Messages/Message.php b/src/Zulip/Messages/Message.php
index 58c66b96..1240c420 100644
--- a/src/Zulip/Messages/Message.php
+++ b/src/Zulip/Messages/Message.php
@@ -12,16 +12,16 @@
 
 namespace Guanguans\Notify\Zulip\Messages;
 
-use Guanguans\Notify\Foundation\Concerns\AsJson;
+use Guanguans\Notify\Foundation\Concerns\AsFormParams;
 use Guanguans\Notify\Foundation\Concerns\AsPost;
 
 class Message extends \Guanguans\Notify\Foundation\Message
 {
-    use AsJson;
+    use AsFormParams;
     use AsPost;
 
-    public function toHttpUri()
+    public function toHttpUri(): string
     {
-        return '%s/api/v1/messages';
+        return 'api/v1/messages';
     }
 }
diff --git a/src/Zulip/Messages/PrivateMessage.php b/src/Zulip/Messages/PrivateMessage.php
deleted file mode 100644
index e2c70ba1..00000000
--- a/src/Zulip/Messages/PrivateMessage.php
+++ /dev/null
@@ -1,61 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-/**
- * This file is part of the guanguans/notify.
- *
- * (c) guanguans <ityaozm@gmail.com>
- *
- * This source file is subject to the MIT license that is bundled.
- */
-
-namespace Guanguans\Notify\Zulip\Messages;
-
-/**
- * @method \Guanguans\Notify\Zulip\Messages\PrivateMessage type($type)
- * @method \Guanguans\Notify\Zulip\Messages\PrivateMessage to($to)
- * @method \Guanguans\Notify\Zulip\Messages\PrivateMessage content($content)
- */
-class PrivateMessage extends Message
-{
-    /**
-     * @var array<string>
-     */
-    protected array $defined = [
-        'type',
-        'to',
-        'content',
-    ];
-
-    /**
-     * @var array<string>
-     */
-    protected array $required = [
-        'type',
-        'to',
-        'content',
-    ];
-
-    /**
-     * @var array<string>
-     */
-    protected array $defaults = [
-        'type' => 'private',
-    ];
-
-    /**
-     * @var array<array<\string>>
-     */
-    protected array $allowedValues = [
-        'type' => ['private'],
-    ];
-
-    public function __construct(string $to, string $content)
-    {
-        parent::__construct([
-            'to' => $to,
-            'content' => $content,
-        ]);
-    }
-}
diff --git a/src/Zulip/Messages/StreamMessage.php b/src/Zulip/Messages/StreamMessage.php
index 76584a7c..1cd2cdd3 100644
--- a/src/Zulip/Messages/StreamMessage.php
+++ b/src/Zulip/Messages/StreamMessage.php
@@ -22,9 +22,6 @@
  */
 class StreamMessage extends Message
 {
-    /**
-     * @var array<string>
-     */
     protected array $defined = [
         'type',
         'to',
@@ -34,9 +31,6 @@ class StreamMessage extends Message
         'local_id',
     ];
 
-    /**
-     * @var array<string>
-     */
     protected array $required = [
         'type',
         'to',
@@ -45,23 +39,17 @@ class StreamMessage extends Message
     ];
 
     protected array $allowedTypes = [
-        'to' => ['string', 'int'],
+        'to' => ['string', 'int', 'array'],
         'content' => 'string',
         'topic' => 'string',
         'queue_id' => 'string',
         'local_id' => 'string',
     ];
 
-    /**
-     * @var array<string>
-     */
     protected array $defaults = [
         'type' => 'stream',
     ];
 
-    /**
-     * @var array<array<\string>>
-     */
     protected array $allowedValues = [
         'type' => ['stream'],
     ];