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Free Online HTML Validator

Use this free online HTML Validator to verify that your HTML document complies with accepted syntax rules and structural standards. Enter your HTML into the editor or upload an HTML file, then run the validation to check for markup errors, invalid elements, missing tags, and other issues that may affect document validity.

For improved readability, you can use our HTML Formatter to organize and format your HTML document.

HTML Validator

HTML Validation Example Document

Valid HTML Document

The following HTML is valid because all tags are properly opened and closed, elements are correctly nested, and the document includes the required structure.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Company Profile</title>
</head>
<body>
    <header>
        <h1>ABC Technologies</h1>
    </header>

    <main>
        <p>We provide web development and cloud solutions for businesses.</p>

        <ul>
            <li>Website Design</li>
            <li>Mobile Apps</li>
            <li>Cloud Hosting</li>
        </ul>
    </main>

    <footer>
        <p>&copy; 2026 ABC Technologies</p>
    </footer>
</body>
</html>

Invalid HTML Document

The following HTML is invalid because several tags are missing their closing tags, the list is not properly closed, and the paragraph is incorrectly nested inside the heading.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Company Profile</title>
</head>
<body>
    <header>
        <h1>ABC Technologies
        <p>We provide web development and cloud solutions.</h1>
    </header>

    <main>
        <ul>
            <li>Website Design
            <li>Mobile Apps
            <li>Cloud Hosting
        </ul>
    </main>

    <footer>
        <p>&copy; 2026 ABC Technologies
</body>
</html>

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