One tool, and a deliberately narrow one: a discounted cash flow model built from figures you type. No market data is fetched, live or historical, and no figure leaves the page.
It is educational. There is no advice, no recommendation, no rating and no signal, and the output is no better than the assumptions behind it. The sensitivity grid exists because a DCF produces a range rather than a number, and the width of that range is itself information.
What people use these for
Learning what each assumption in a DCF actually does to the answer.
Testing how much of a valuation depends on the terminal value rather than the forecast.
Exporting a model and its inputs as JSON or CSV to check the arithmetic elsewhere.
Privacy in this section
Every calculation is arithmetic performed in the browser. No market-data API is contacted and no figures are transmitted or stored.