Why this site exists
PromptVault is a small collection of tools built to do one job quickly, without an account, without tracking you across the web and without burying the answer under three pop-ups. Everything you type stays in your browser.
Is it really free?
Yes. The tools are free and there is no signup. The site is kept online by advertising and, where relevant, affiliate links to products we think are genuinely useful. A commission from a qualifying purchase costs you nothing extra.
Accuracy
The calculators use standard formulas and double-precision arithmetic. They are suitable for everyday use. For anything with financial, medical or legal consequences, confirm the result with the relevant professional or official source.