diff --git a/Libraries/LibWeb/Bindings/WindowObject.cpp b/Libraries/LibWeb/Bindings/WindowObject.cpp
index 7c321f86611..a078548d5d1 100644
--- a/Libraries/LibWeb/Bindings/WindowObject.cpp
+++ b/Libraries/LibWeb/Bindings/WindowObject.cpp
@@ -24,8 +24,11 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <AK/Base64.h>
+#include <AK/ByteBuffer.h>
 #include <AK/FlyString.h>
 #include <AK/Function.h>
+#include <AK/String.h>
 #include <LibJS/Interpreter.h>
 #include <LibJS/Runtime/Error.h>
 #include <LibJS/Runtime/Function.h>
@@ -60,6 +63,8 @@ void WindowObject::initialize()
     define_native_function("setTimeout", set_timeout, 1);
     define_native_function("requestAnimationFrame", request_animation_frame, 1);
     define_native_function("cancelAnimationFrame", cancel_animation_frame, 1);
+    define_native_function("atob", atob, 1);
+    define_native_function("btoa", btoa, 1);
 
     define_property("navigator", heap().allocate<NavigatorObject>(*this, *this), JS::Attribute::Enumerable | JS::Attribute::Configurable);
     define_property("location", heap().allocate<LocationObject>(*this, *this), JS::Attribute::Enumerable | JS::Attribute::Configurable);
@@ -205,6 +210,34 @@ JS_DEFINE_NATIVE_FUNCTION(WindowObject::cancel_animation_frame)
     return JS::js_undefined();
 }
 
+JS_DEFINE_NATIVE_FUNCTION(WindowObject::atob)
+{
+    auto* impl = impl_from(interpreter);
+    if (!impl)
+        return {};
+    if (!interpreter.argument_count())
+        return interpreter.throw_exception<JS::TypeError>(JS::ErrorType::BadArgCountOne, "atob");
+    auto string = interpreter.argument(0).to_string(interpreter);
+    if (interpreter.exception())
+        return {};
+    auto decoded = decode_base64(StringView(string));
+    return JS::js_string(interpreter, String::copy(decoded));
+}
+
+JS_DEFINE_NATIVE_FUNCTION(WindowObject::btoa)
+{
+    auto* impl = impl_from(interpreter);
+    if (!impl)
+        return {};
+    if (!interpreter.argument_count())
+        return interpreter.throw_exception<JS::TypeError>(JS::ErrorType::BadArgCountOne, "btoa");
+    auto string = interpreter.argument(0).to_string(interpreter);
+    if (interpreter.exception())
+        return {};
+    auto encoded = encode_base64(StringView(string));
+    return JS::js_string(interpreter, String::copy(encoded));
+}
+
 JS_DEFINE_NATIVE_GETTER(WindowObject::document_getter)
 {
     auto* impl = impl_from(interpreter, global_object);
diff --git a/Libraries/LibWeb/Bindings/WindowObject.h b/Libraries/LibWeb/Bindings/WindowObject.h
index 3bc6797249e..731c2083d95 100644
--- a/Libraries/LibWeb/Bindings/WindowObject.h
+++ b/Libraries/LibWeb/Bindings/WindowObject.h
@@ -60,6 +60,8 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(set_timeout);
     JS_DECLARE_NATIVE_FUNCTION(request_animation_frame);
     JS_DECLARE_NATIVE_FUNCTION(cancel_animation_frame);
+    JS_DECLARE_NATIVE_FUNCTION(atob);
+    JS_DECLARE_NATIVE_FUNCTION(btoa);
 
     NonnullRefPtr<Window> m_impl;