About Toolzeroo
Toolzeroo is an independent website of free online tools: more than 120 calculators, converters, text, developer and image tools that work in your browser, with no sign-up.
What the site is
Each tool does one job: work out a percentage, convert a unit, count words, format JSON, resize an image. Every tool page explains how the result is worked out, with a worked example and the assumptions it makes, so you can check the answer yourself. The guides explain the maths and methods behind the most-used tools.
Toolzeroo also runs Toolzeroo Finance (South African money calculators, with its own About page), Toolzeroo Kitchen (recipes), a resume builder and fan games.
Who runs it
Toolzeroo is a small independent site run from South Africa. It is not part of any larger company, and no business pays to appear on it or to change what a tool shows.
How the tools work
- In your browser. Calculations, text and files are handled on your own device. Files you open in the image tools are not uploaded. You do not need an account.
- Light, anonymous counts. The site counts which tool was opened or used, so we know what to improve. It does not record what you type.
- Paid for by ads. The site is free and is paid for by advertising from Google AdSense. Google chooses the ads. See the privacy notice for how ads use cookies.
How we build and check the tools
- Standard formulas, shown on the page. Tools use standard, published formulas and conversion factors, and each page says which one it uses.
- Tested against worked examples. The calculators have automated tests that check their answers against worked examples.
- Written with AI help, checked before publishing. Pages and code are written and maintained with the help of AI tools. Before a new tool or guide is published, a separate review checks its formulas, examples and claims.
- General information only. Results are estimates based on what you enter. For health, money, legal or safety decisions, check with a qualified professional. See the disclaimer.
Corrections
If a result, formula or explanation looks wrong, please tell us at social@toolzeroo.com with the tool name and the values you entered. We check every report, fix confirmed errors and update the page.
Questions or ideas for a new tool? See the contact page.
Last updated 23 October 2026.