What this site is
Most online utilities ask you to upload a file or paste your data into a form that posts it to a server. util·tools does the opposite: every calculator, converter and test on this site is plain HTML, CSS and JavaScript that runs on your own device. There is no account, no upload and no waiting on a server, which is why results appear as you type.
That design has a practical consequence worth stating plainly — the numbers, text and dates you type never leave your computer, because there is nowhere for them to go. It also means the tools keep working on a slow connection, and they load in well under a second.
How the tools are built
Each tool is one page with one job. There is no framework, no bundler and no tracking script; a typical page is under 10 KB of HTML plus a shared stylesheet. Calculations are written as small, testable functions and covered by a unit-test suite that runs before anything is published, so a change to one tool cannot quietly break another.
Where a tool makes a judgement call — whether a date range includes its end date, whether a number is grouped in thousands or in lakh and crore — the page says which convention it uses rather than leaving you to guess.
What we do not do
We do not require sign-up, we do not store what you type, and we do not sell personal information. Some pages carry advertising to cover hosting; how that works is described in our Privacy Policy, and any affiliate links are declared in our Disclosure.
Corrections
If a tool gives an answer you believe is wrong, that is worth reporting — a wrong calculator is worse than no calculator. Please include the exact input you used and the answer you expected.