diff --git a/Userland/Libraries/LibWeb/Infra/CharacterTypes.h b/Userland/Libraries/LibWeb/Infra/CharacterTypes.h
new file mode 100644
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+++ b/Userland/Libraries/LibWeb/Infra/CharacterTypes.h
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+/*
+ * Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+
+namespace Web::Infra {
+
+// https://infra.spec.whatwg.org/#ascii-whitespace
+constexpr bool is_ascii_whitespace(u32 code_point)
+{
+    // ASCII whitespace is U+0009 TAB, U+000A LF, U+000C FF, U+000D CR, or U+0020 SPACE.
+    return code_point == '\t' || code_point == '\n' || code_point == '\f' || code_point == '\r' || code_point == ' ';
+}
+
+}