HTML Structure Checker
Check a page for the structural and SEO basics: title, description, one H1, lang, viewport, canonical and alt text.
Your result will appear here as soon as you add some input.
How to use it
- 1Paste your input into the input box, or type it directly.
- 2Adjust the options if you need something other than the defaults.
- 3The result updates as you type.
- 4Copy the result to your clipboard or download it as a file.
About the HTML Structure Checker
These are the checks that can be made by reading the source: whether the page has a title and a description, exactly one H1, a lang attribute, a viewport meta tag, a canonical link, and alt text on its images.
It also reports elements that appear to be opened and never closed, which is usually the cause when a layout collapses after one section.
This is not a replacement for the W3C validator, which checks the full HTML grammar. It is the subset that matters most for search and accessibility.
Questions people ask
Is your code uploaded to a server?
No. This tool runs entirely in your browser using standard web APIs, so your code never leaves your device. You can confirm it by opening your browser's network panel while the tool runs, or by disconnecting from the internet after the page has loaded.
Is it free, and do I need an account?
Yes, it is free, and there is no account, no sign-up and no watermark on the result. The project is funded by optional donations.