Open a chart’s Export menu and click Copy share link. The whole chart, settings and values, travels compressed inside the link itself (the part after the #). Nothing is uploaded and there is no account: the viewer page rebuilds the chart locally in the recipient’s browser, and that part of the link never reaches our server.
Treat a share link like the chart it contains: anyone you give it to can see the data in it. If a chart has too much data for a link, Deltaline tells you so; use Download HTML instead.