HTML Validator
Check HTML for unclosed and mismatched tags, duplicate ids, missing alt text and other common errors, with line numbers. Your work stays on this device whenever possible.
How to use HTML Validator
- Paste your HTML, or open an .html file.
- Press "Validate HTML".
- Read the list of errors and warnings, sorted by line.
- Click a line number to jump to that spot in the code, fix it, and validate again.
Worked example
A landing page shows its footer in the wrong place. The validator reports "<div> (line 42) is not closed before </section> on line 88". Adding the missing </div> puts the footer back.
When to use this tool
- Finding the unclosed tag that breaks a page layout.
- Checking email templates, CMS snippets and theme files before publishing.
Important limitations
Covers the common structural and accessibility errors, not every rule of the HTML specification; use the W3C validator for full conformance checks.
Frequently asked questions
What does this HTML checker find?
Tags that are never closed, closed in the wrong order or closed without being opened; duplicate ids and duplicate attributes; images without alt or src; nested links and forms; missing doctype, title, charset, viewport and lang; self-closing syntax on non-void elements; and obsolete tags like <center> and <font>.
Why is a missing </p> or </li> not an error?
HTML lets you leave out some end tags, including </p>, </li>, </td> and </tr>. The checker follows those rules: for example, a new <li> closes the previous one, and a <div> closes an open <p>.
Is it the same as the W3C validator?
No. It checks the common mistakes above instantly and privately, but it does not implement every rule in the HTML specification, such as which elements may appear inside which. Use the W3C validator for a full conformance check.
Does it check a live URL?
No. Paste the HTML or open a file. To get a live page's code, open it in your browser and use View Source.
Is my code uploaded?
No. It is checked in your browser.