diff --git a/README.md b/README.md
index 35a14bc..c9ac868 100644
--- a/README.md
+++ b/README.md
@@ -274,6 +274,7 @@ Below is list of all available validation rules
 * [email](#rule-email)
 * [uppercase](#rule-uppercase)
 * [lowercase](#rule-lowercase)
+* [json](#rule-json)
 * [alpha](#rule-alpha)
 * [numeric](#rule-numeric)
 * [alpha_num](#rule-alpha_num)
@@ -404,6 +405,11 @@ The field under this validation must be valid uppercase.
 
 The field under this validation must be valid lowercase.
 
+<a id="rule-json"></a>
+#### json
+
+The field under this validation must be valid JSON string.
+
 <a id="rule-alpha"></a>
 #### alpha
 
diff --git a/src/Rules/Json.php b/src/Rules/Json.php
new file mode 100644
index 0000000..3a9337b
--- /dev/null
+++ b/src/Rules/Json.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace Rakit\Validation\Rules;
+
+use Rakit\Validation\Rule;
+
+class Json extends Rule
+{
+
+    protected $message = "The :attribute must be a valid JSON string";
+
+    public function check($value)
+    {
+        if (! is_string($value) || empty($value)) {
+            return false;
+        }
+        
+        json_decode($value);
+
+        if (json_last_error() !== JSON_ERROR_NONE) {
+            return false;
+        }
+
+        return true;
+    }
+
+}
\ No newline at end of file
diff --git a/src/Validator.php b/src/Validator.php
index 0bfba9c..80c5046 100644
--- a/src/Validator.php
+++ b/src/Validator.php
@@ -106,6 +106,7 @@ protected function registerBaseValidators()
             'after'                     => new Rules\After,
             'lowercase'                 => new Rules\Lowercase,
             'uppercase'                 => new Rules\Uppercase,
+            'json'                      => new Rules\Json,
             'defaults'                  => new Rules\Defaults,
             'default'                   => new Rules\Defaults, // alias of defaults
         ];
diff --git a/tests/Fixtures/Even.php b/tests/Fixtures/Even.php
new file mode 100644
index 0000000..cc0ea6d
--- /dev/null
+++ b/tests/Fixtures/Even.php
@@ -0,0 +1,18 @@
+<?php
+
+
+class Even extends \Rakit\Validation\Rule
+{
+
+    protected $message = "The :attribute must be even";
+
+    public function check($value)
+    {
+        if ( ! is_numeric($value)) {
+            return false;
+        }
+
+        return $value % 2 === 0;
+    }
+
+}
diff --git a/tests/Fixtures/Json.php b/tests/Fixtures/Json.php
deleted file mode 100644
index c92816e..0000000
--- a/tests/Fixtures/Json.php
+++ /dev/null
@@ -1,20 +0,0 @@
-<?php
-
-
-class Json extends \Rakit\Validation\Rule
-{
-
-    protected $message = "This :attribute is not a valid json object";
-
-    public function check($value)
-    {
-
-        json_decode($value);
-
-        if (json_last_error() !== JSON_ERROR_NONE) {
-            return false;
-        }
-
-        return true;
-    }
-}
diff --git a/tests/Rules/JsonTest.php b/tests/Rules/JsonTest.php
new file mode 100644
index 0000000..aa5377f
--- /dev/null
+++ b/tests/Rules/JsonTest.php
@@ -0,0 +1,33 @@
+<?php
+
+use Rakit\Validation\Rules\Json;
+
+class JsonTest extends PHPUnit_Framework_TestCase
+{
+
+    public function setUp()
+    {
+        $this->rule = new Json;
+    }
+
+    public function testValids()
+    {
+        $this->assertTrue($this->rule->check('{}'));
+        $this->assertTrue($this->rule->check('[]'));
+        $this->assertTrue($this->rule->check('false'));
+        $this->assertTrue($this->rule->check('null'));
+        $this->assertTrue($this->rule->check('{"username": "John Doe"}'));
+        $this->assertTrue($this->rule->check('{"number": 12345678}'));
+    }
+
+    public function testInvalids()
+    {
+        $this->assertFalse($this->rule->check(''));
+        $this->assertFalse($this->rule->check(123));
+        $this->assertFalse($this->rule->check(false));
+        $this->assertFalse($this->rule->check('{"username": John Doe}'));
+        $this->assertFalse($this->rule->check('{number: 12345678}'));
+    }
+
+}
+
diff --git a/tests/ValidatorTest.php b/tests/ValidatorTest.php
index dc7827f..9a06036 100644
--- a/tests/ValidatorTest.php
+++ b/tests/ValidatorTest.php
@@ -2,7 +2,7 @@
 
 use Rakit\Validation\Validator;
 
-require_once 'Fixtures/Json.php';
+require_once 'Fixtures/Even.php';
 require_once 'Fixtures/Required.php';
 
 class ValidatorTest extends PHPUnit_Framework_TestCase
@@ -339,11 +339,11 @@ public function testAfterRule()
     public function testNewValidationRuleCanBeAdded()
     {
 
-        $this->validator->addValidator('json', new Json());
+        $this->validator->addValidator('even', new Even());
 
-        $data = ['s' => json_encode(['name' => 'space x', 'human' => false])];
+        $data = [4, 6, 8, 10 ];
 
-        $validation = $this->validator->make($data, ['s' => 'json'], []);
+        $validation = $this->validator->make($data, ['s' => 'even'], []);
 
         $validation->validate();