What is HTML Validator?
HTML Validator inspects HTML code for syntax errors, unclosed tags, and improper nesting.
How to use HTML Validator
Paste HTML markup to validate structure and review syntax errors.
Key features
- HTML structural validation
- 100% client-side operation
Common use cases
- Checking website markup for invalid tags before publishing
Technical details & standards
Parses DOM element hierarchy client-side.
Frequently asked questions
Can it validate HTML5?
Yes, HTML5 semantic elements are fully supported.
Is my data safe?
All processing happens entirely in your browser. Your data never leaves your device and is never sent to or stored on a server.
Does it work offline?
Yes. Once the page has loaded, most tools keep working without an internet connection.