WordHub stores vocabulary, settings, and authentication tokens locally in browser storage. When you sign in, saved words and learning progress may be synced with WordHub services at wordhub.top and api.wordhub.top. Selected words or page text are sent to WordHub APIs only to provide lookup, translation, AI context, and learning features. We do not sell personal data. You can use the extension without signing in for local lookup features, and you can remove stored data by uninstalling the extension or signing out. For privacy questions, contact support@wordhub.top.