This tool processes your CSV entirely within your browser.
The selected file is read locally using browser JavaScript and is not uploaded to any external entity of any kind.
Your data is kept only in browser memory while this tab remains open. When the tab or browser window is closed, that in-memory data is cleared.
The tool does not store membership data in localStorage, sessionStorage, cookies, or any remote database.
Additional hardening: this page disables browser form submission behavior and turns off autocomplete on its controls to reduce the chance of accidental persistence or transmission.