diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 19a3da0aae..1b792305c1 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -152,6 +152,7 @@ Yii Framework 2 Change Log
 - Enh #4297: Added check for DOM extension to requirements (samdark)
 - Enh #4317: Added `absoluteAuthTimeout` to yii\web\User (ivokund, nkovacs)
 - Enh #4360: Added client validation support for file validator (Skysplit)
+- Enh #4436: Added callback functions to AJAX-based form validation (thiagotalma)
 - Enh: Added support for using sub-queries when building a DB query with `IN` condition (qiangxue)
 - Enh: Supported adding a new response formatter without the need to reconfigure existing formatters (qiangxue)
 - Enh: Added `yii\web\UrlManager::addRules()` to simplify adding new URL rules (qiangxue)
diff --git a/framework/assets/yii.activeForm.js b/framework/assets/yii.activeForm.js
index 194fb7de1c..9f8c6159d3 100644
--- a/framework/assets/yii.activeForm.js
+++ b/framework/assets/yii.activeForm.js
@@ -44,6 +44,12 @@
         // a callback that is called after an attribute is validated. The signature of the callback should be:
         // function ($form, attribute, messages)
         afterValidate: undefined,
+        // a pre-request callback function on AJAX-based validation. The signature of the callback should be:
+        // function ($form, jqXHR, textStatus)
+        ajaxBeforeSend: undefined,
+        // a function to be called when the request finishes on AJAX-based validation. The signature of the callback should be:
+        // function ($form, jqXHR, textStatus)
+        ajaxComplete: undefined,
         // the GET parameter name indicating an AJAX-based validation
         ajaxParam: 'ajax',
         // the type of data that you're expecting back from the server
@@ -306,6 +312,16 @@
                 type: $form.prop('method'),
                 data: $form.serialize() + extData,
                 dataType: data.settings.ajaxDataType,
+                complete: function (jqXHR, textStatus) {
+                    if (data.settings.ajaxComplete) {
+                        data.settings.ajaxComplete($form, jqXHR, textStatus);
+                    }
+                },
+                beforeSend: function (jqXHR, textStatus) {
+                    if (data.settings.ajaxBeforeSend) {
+                        data.settings.ajaxBeforeSend($form, jqXHR, textStatus);
+                    }
+                },
                 success: function (msgs) {
                     if (msgs !== null && typeof msgs === 'object') {
                         $.each(data.attributes, function () {
diff --git a/framework/widgets/ActiveForm.php b/framework/widgets/ActiveForm.php
index 5794d8a4f2..2821c22e18 100644
--- a/framework/widgets/ActiveForm.php
+++ b/framework/widgets/ActiveForm.php
@@ -151,6 +151,26 @@ class ActiveForm extends Widget
      * ~~~
      */
     public $afterValidate;
+    /**
+     * @var string|JsExpression a JS pre-request callback function on AJAX-based validation.
+     * The signature of the callback should be:
+     *
+     * ~~~
+     * function ($form, jqXHR, textStatus) {
+     * }
+     * ~~~
+     */
+    public $ajaxBeforeSend;
+    /**
+     * @var string|JsExpression a JS callback to be called when the request finishes on AJAX-based validation.
+     * The signature of the callback should be:
+     *
+     * ~~~
+     * function ($form, jqXHR, textStatus) {
+     * }
+     * ~~~
+     */
+    public $ajaxComplete;
     /**
      * @var array the client validation options for individual attributes. Each element of the array
      * represents the validation options for a particular attribute.
@@ -208,7 +228,7 @@ class ActiveForm extends Widget
         if ($this->validationUrl !== null) {
             $options['validationUrl'] = Url::to($this->validationUrl);
         }
-        foreach (['beforeSubmit', 'beforeValidate', 'afterValidate'] as $name) {
+        foreach (['beforeSubmit', 'beforeValidate', 'afterValidate', 'ajaxBeforeSend', 'ajaxComplete'] as $name) {
             if (($value = $this->$name) !== null) {
                 $options[$name] = $value instanceof JsExpression ? $value : new JsExpression($value);
             }