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HTML Validator.

Check HTML for errors like the W3C validator — paste code, upload a file or enter a URL.

Tip: Ctrl + Enter starts the check. HTML without <html> or <title> is checked as a page fragment.

File

The public file is downloaded once (max 2 MB, up to 5 redirects). Local and private network addresses are blocked.

Ready.

The code is checked in memory only and is never stored or logged. The checks follow the HTML Living Standard, CSS and XML specifications and cover the most common errors, but they are not a complete replacement for the official W3C validators.