Flow2API Token Updater is a local browser extension for users who run their own Flow2API service. During setup, the user enters a Flow2API address plus username and password once. The extension sends that login only to the user's own Flow2API server to obtain an internal plugin connection credential for later syncs, and does not keep the password as the long-term runtime credential. After setup, the extension reads the Google Labs session cookie from labs.google and syncs the current browser profile's session only to the user's own Flow2API endpoint at /api/plugin/update-token. Local sync state, the remembered Labs session context, and logs are stored in browser local storage. In Firefox-based browsers, recent sync state and the remembered Labs session context are scoped to the active cookie store or container so different signed-in accounts inside one profile do not overwrite each other. If a reusable browser login still exists but the related Google page is not open, the extension may silently open labs.google in a background tab to rediscover the session and then close the temporary tab. Before overwriting an existing Flow2API token, the extension attempts to validate the candidate Labs session and ignores stale Labs cookies whose browser expiration date is misleadingly long; if a candidate session cannot be validated yet, the extension keeps the current token and retries later instead of overwriting it blindly. The extension does not send analytics, advertising, telemetry, or tracking data to the developer.