Claude RTL Toolkit does not collect, transmit, or share any personal data. It stores only your own preferences (fonts, sizes, language, and direction choices) locally via the browser's extension storage. Direction choices may sync across your own signed-in browsers via the browser's built-in sync; this data never reaches the developer. No analytics, no tracking, and no external network requests — fonts are bundled inside the extension. The extension only changes how text is displayed on claude.ai.