DenyOut is local-first. Protect and app update checks work without an account. Optional sign-in only syncs settings you choose.
Sign in only if you want settings sync across machines. You can delete cloud data from Settings. Sync never uploads audit bodies or secret-looking URLs.
The desktop product does not send product telemetry. This website and the optional account API keep anonymous totals only (for example how often the update file was fetched, and how many accounts exist). No emails or names appear in those totals. Owner operations use a private stats view - it is not linked from the main menu.