Lesefluss does not transmit personal data, page content or usage data. It uses no telemetry, advertising or external services. Speed, direction, other settings and their associated website origins are stored only in Firefox's local extension storage. Speed and direction changes in private windows are not written to persistent website settings. Per-tab scrolling state is stored only for the current browser session. Optional website access enables single-key shortcuts, automatic start and continuation after navigation, and is granted only with your consent.