diff --git a/packages/shared-base/src/Messages/Shared.ts b/packages/shared-base/src/Messages/Shared.ts
new file mode 100644
index 000000000000..1bc24f53efe0
--- /dev/null
+++ b/packages/shared-base/src/Messages/Shared.ts
@@ -0,0 +1,17 @@
+import { WebExtensionMessage } from '@dimensiondev/holoflows-kit'
+
+/**
+ * @deprecated
+ * Prefer MaskMessages.
+ *
+ * Only use this in the following cases:
+ *
+ * - You need to send message across different plugins
+ *       e.g. from the packages/plugins/Example to packages/plugins/Example2
+ * - You need to send message from plugin
+ *       e.g. packages/plugins/Example to the main Mask extension.
+ */
+// TODO: find a way to use a good API for cross isolation communication.
+export const CrossIsolationMessages = new WebExtensionMessage<CrossIsolationEvents>({ domain: '_' })
+
+export interface CrossIsolationEvents {}
diff --git a/packages/shared-base/src/index.ts b/packages/shared-base/src/index.ts
index a8c38e51d931..4a484473aba0 100644
--- a/packages/shared-base/src/index.ts
+++ b/packages/shared-base/src/index.ts
@@ -14,6 +14,7 @@ export * from './Persona/type'
 export * from './Site/type'
 export * from './Routes'
 export * from './Messages/Mask'
+export * from './Messages/Shared'
 export * from './Results'
 export * from './convert'
 export * from './NextID/type'