About

Website Checker is a single-purpose site: one free website checker that works in the browser, with the method explained next to the result.

Testing before every update

Every release of the website checker is checked by an automated test suite of 102 checks in a real browser — normal values, edge cases and invalid input — and on desktop and phone screen sizes before it goes live.

References

Explanations are based on primary sources and recognised references, which are linked in the text (for example rfc-editor.org).

Our approach

Pages are written and maintained by the site's editorial team. We aim to answer the question people actually ask, show worked examples with real numbers, and say plainly where a calculator cannot replace professional advice. Nothing on this site is sponsored content.

Updates and corrections

Published October 8, 2026, last reviewed October 12, 2026. Corrections are welcome via the contact page; confirmed fixes go out with the next update.

Advertising

The tool is free to use. The site is funded by advertising, which never influences results or explanations.

— Website Checker editorial team