HTML Validator
Validate HTML markup for structural errors and parse issues. Identifies unclosed tags, missing attributes, and malformed content.
DevForge is free and ad-supported. Buy me a coffee if it saved you time.
How to Use This Tool
Paste your HTML snippet or full document into the input field and click Validate. The tool checks for unclosed tags, missing required attributes, deprecated elements, and other common issues.
Common Use Cases
- Catch unclosed tags before shipping HTML templates
- Identify missing alt attributes for accessibility
- Find deprecated HTML elements in legacy codebases
Frequently Asked Questions
How does the HTML validator work?
It uses the browser's built-in DOMParser to parse your HTML as XML (XHTML strict mode), which surfaces unclosed tags, missing quotes, and other structural errors that the lenient HTML5 parser would silently fix.
Why does valid HTML5 sometimes show errors?
HTML5 allows many constructs (like self-closing div tags) that XML does not. This tool catches hard errors and structural issues rather than full W3C HTML5 conformance checking.
Is my data sent to a server?
No. All validation happens in your browser. Your data never leaves your machine.