diff --git a/CHANGELOG.md b/CHANGELOG.md
index a7ea194..13dd7c0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,15 @@
 # Changelog
 
-All notable changes to `laravel-mixins` will be documented in this file
+All notable changes to `laravel-mixins` will be documented in this file.
 
-## 1.0.0 - 2020-08-xx
+## 2.1.0 - 2020-10-13
 
-- Initial release
+- Added `InKeys` rule.
+
+## 2.0.0 - 2020-10-05
+
+- [ConvertsBase64ToFiles] Renamed `base64ImageKeys` to `base64FileKeys`.
+
+## 1.0.0 - 2020-09-22
+
+- Initial release.
diff --git a/README.md b/README.md
index e67cae3..4c6a504 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,7 @@ There's no Service Provider or automatic discovery/registration of anything. All
 * [Current password](#current-password)
 * [Dimensions With Margin](#dimensions-with-margin)
 * [Host](#host)
+* [In Keys](#in-keys)
 * [Max Words](#max-words)
 * [URL Without Scheme](#url-without-scheme)
 
@@ -163,6 +164,22 @@ use ProtoneMedia\LaravelMixins\Rules\Host;
 $rule = Host::make(['facebook.com', 'fb.me']);
 ```
 
+### In Keys
+
+Verifies if the given key or index exists in the array.
+
+```php
+use ProtoneMedia\LaravelMixins\Rules\InKeys;
+
+$rule = new InKeys(['laravel' => 'Laravel Framework', 'tailwindcss' => 'Tailwind CSS framework']);
+
+// same as
+
+use Illuminate\Validation\Rules\In;
+
+$rule = new In(['laravel', 'tailwindcss']);
+```
+
 ### Max Words
 
 Passes if the values contains no more words than specified.
diff --git a/src/Rules/InKeys.php b/src/Rules/InKeys.php
new file mode 100644
index 0000000..bb31d1e
--- /dev/null
+++ b/src/Rules/InKeys.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace ProtoneMedia\LaravelMixins\Rules;
+
+use Illuminate\Validation\Rules\In;
+
+class InKeys extends In
+{
+    /**
+     * Create a new rule instance with the keys of the given values.
+     *
+     * @param  array  $values
+     * @return void
+     */
+    public function __construct(array $values)
+    {
+        $this->values = array_keys($values);
+    }
+
+    public static function make(array $values): self
+    {
+        return new static($values);
+    }
+}
diff --git a/tests/Rules/InKeysTest.php b/tests/Rules/InKeysTest.php
new file mode 100644
index 0000000..76317a1
--- /dev/null
+++ b/tests/Rules/InKeysTest.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace ProtoneMedia\Mixins\Tests\Rules;
+
+use Illuminate\Support\Facades\Validator;
+use Orchestra\Testbench\TestCase;
+use ProtoneMedia\LaravelMixins\Rules\InKeys;
+
+class InKeysTest extends TestCase
+{
+    /** @test */
+    public function it_validates_the_keys()
+    {
+        $rule = InKeys::make([
+            'a' => 'foo',
+            'b' => 'bar',
+            'c' => 'baz',
+        ]);
+
+        $validator = Validator::make([], ['attribute' => $rule]);
+
+        $this->assertTrue($validator->setData(['attribute' => 'a'])->passes());
+        $this->assertFalse($validator->setData(['attribute' => 'd'])->passes());
+        $this->assertFalse($validator->setData(['attribute' => 'foo'])->passes());
+    }
+}