LugalVault's full privacy policy, which explicitly covers this browser extension, is available at https://app.lugalvault.com/privacy-policy.

Summary for this extension: it communicates only with https://api.lugalvault.com over HTTPS. It transmits your account sign-in information, authentication tokens, and the vocabulary entries you choose to save. It locally stores session tokens, limited account display information, and a device identifier. It never reads the pages you visit, your history, or your clipboard. Data is not sold and is used only to provide the vocabulary-saving features.