About ZoolTools

ZoolTools is a collection of 114 free online tools and calculators across 9 categories — image and PDF utilities, text and developer tools, unit and currency converters, and finance, tax and health calculators — plus 16 in-depth guides explaining the maths behind them. It is built and operated by Ujjwal Technolabs, a small independent software team.

Why we built it

Most online tool sites make you wait through an upload, then hand back a number with no explanation of where it came from. We wanted the opposite: open a page, get the answer immediately, and be able to see the formula and a worked example if you care to check. Our own team kept opening five different sites to compute an EMI, extract GST from an invoice and strip metadata from a screenshot — so we built one place that does all three properly.

Privacy by design, not by policy

Image, PDF and text tools run entirely in your browser. Compression, conversion, page merging, watermarking and metadata removal all happen on your own device, so your files are never uploaded to a server — there is no upload step to speak of. That is an architectural choice rather than a promise we ask you to trust: it is also why these tools stay fast on a poor connection. What the site itself collects (analytics and advertising) is set out in our privacy policy.

How we keep the numbers right

Every calculator’s maths lives in one shared module with a file of hand-authored test vectors beside it — expected results written from the published formula, never generated from our own output. The website and our mobile app both run against that same vector file, which is why a calculation here matches the app exactly. Time-sensitive figures such as tax slabs and statutory rates are labelled with the year they apply to, and where a tool models a simplified version of a rule, the page says so. The full process is documented in how we build and test our tools.

Free, and how that is paid for

There is no sign-up, no paywall and no feature held back. ZoolTools is funded by advertising, which we keep out of the way: ads appear around content, never inside a result and never styled to look like a button you are meant to press. No calculator result, ranking or recommendation is influenced by an advertiser, and nothing on the site is sponsored placement.

Limits worth stating plainly

Finance and tax outputs are estimates for planning, not tax, investment or legal advice — for a filing or a loan agreement, confirm the figures with the official source, your lender or a qualified accountant. Health outputs are general guidance and no substitute for a clinician. Our disclaimer covers this in full.

Get in touch

Found a wrong number, an out-of-date rate, or a tool you wish existed? Write to us at ujjwaltechnolabs@gmail.com or use the contact page. Corrections get priority — if you can include the figure you saw and the source you checked against, we can usually fix it the same week. Otherwise, browse all tools to get started.