diff --git a/tests/Helpers/Base64Test.php b/tests/Helpers/Base64Test.php
new file mode 100644
index 0000000..9273ec4
--- /dev/null
+++ b/tests/Helpers/Base64Test.php
@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tvdt\Tests\Helpers;
+
+use PHPUnit\Framework\TestCase;
+use Safe\Exceptions\UrlException;
+use Tvdt\Helpers\Base64;
+
+class Base64Test extends TestCase
+{
+    public function testBase64UrlEncode() {
+        $this->assertEquals('TWFyaWpu', Base64::base64UrlEncode('Marijn'));
+        $this->assertEquals('UGhpbGluZQ', Base64::base64UrlEncode('Philine'));
+
+        $this->assertEquals('_g', Base64::base64UrlEncode(chr(254)));
+        $this->assertEquals('-g', Base64::base64UrlEncode(chr(250)));
+
+    }
+
+    public function testBase64UrlDecode() {
+        $this->assertEquals('Marijn', Base64::base64UrlDecode('TWFyaWpu'));
+        $this->assertEquals('Philine', Base64::base64UrlDecode('UGhpbGluZQ'));
+
+        $this->assertEquals(chr(254), Base64::base64UrlDecode('_g'));
+        $this->assertEquals(chr(250), Base64::base64UrlDecode('-g'));
+    }
+
+    public function testBase64UrlDecodeCanHandlePadding() {
+        $this->assertEquals('Philine', Base64::base64UrlDecode('UGhpbGluZQ=='));
+    }
+
+    public function testBase64UrlDecodeThrowsExceptionOnInvalidInput() {
+        $this->expectException(UrlException::class);
+        Base64::base64UrlDecode('Philine==');
+    }
+}