HTML Validator
Paste up to 1 MiB of HTML for a small set of browser-side document checks. The browser parser repairs malformed markup, so this is not a full standards validator.
A QUICK WALKTHROUGH
How to use this tool
- Paste an HTML document up to 1 MiB.
- Run the local checks.
- Review the listed document and accessibility hints.
Selected checks
Checks for a doctype, html language, title, UTF-8 charset, duplicate IDs, unresolved same-document fragment links, missing image alt attributes, and skipped heading levels.
Not a full HTML validator
The browser HTML parser repairs malformed markup before inspection. This tool does not implement the complete WHATWG or W3C conformance rules.
Local and bounded
Input is parsed in an inert browser document, limited to 1 MiB, and is not uploaded or inserted into the live page.
GOOD TO KNOW
Common questions
Does a clean result mean my HTML is standards compliant?
No. It means only that these selected checks did not find an issue.
Can it inspect another live page?
No. Paste the HTML source you want to review.