diff --git a/Userland/Libraries/LibWeb/HTML/SandboxingFlagSet.h b/Userland/Libraries/LibWeb/HTML/SandboxingFlagSet.h
new file mode 100644
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+++ b/Userland/Libraries/LibWeb/HTML/SandboxingFlagSet.h
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+/*
+ * Copyright (c) 2022, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+namespace Web::HTML {
+
+// https://html.spec.whatwg.org/multipage/origin.html#sandboxing-flag-set
+struct SandboxingFlagSet {
+    enum Flag {
+        SandboxedNavigation = 1u << 0u,
+        SandboxedAuxiliaryNavigation = 1u << 1u,
+        SandboxedTopLevelNavigationWithoutUserActivation = 1u << 2u,
+        SandboxedTopLevelNavigationWithUserActivation = 1u << 3u,
+        SandboxedPlugins = 1u << 4u,
+        SandboxedOrigin = 1u << 5u,
+        SandboxedForms = 1u << 6u,
+        SandboxedPointerLock = 1u << 7u,
+        SandboxedScripts = 1u << 8u,
+        SandboxedAutomaticFeatures = 1u << 9u,
+        SandboxedDocumentDomain = 1u << 10u,
+        SandboxPropagatesToAuxiliaryBrowsingContexts = 1u << 11u,
+        SandboxedModals = 1u << 12u,
+        SandboxedOrientationLock = 1u << 13u,
+        SandboxedPresentation = 1u << 14u,
+        SandboxedDownloads = 1u << 15u,
+        SandboxedCustomProtocols = 1u << 16u,
+    };
+
+    bool is_empty() const { return flags == 0; }
+
+    u32 flags { 0 };
+};
+
+}