JSONToTable

HTML Validator & Checker

Validate HTML syntax, check structure, and analyze HTML documents

HTML Input

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Validation Results

HTML validation results will appear here

Paste HTML in the input area to start validation

How to Validate HTML - Step by Step Guide

Step 1

Input Your HTML Document

Start by entering your HTML document into the validator. You can paste content, upload files, or use sample data.

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Paste HTML content: Copy HTML from web pages, templates, or applications
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Upload HTML files: Select .html or .htm files from your computer for validation
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Use sample HTML: Click "Sample" to load example HTML for testing the validator

Example: Valid HTML Document

Here's a well-formed HTML5 document that will pass validation:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <title>My Page</title>
</head>
<body>
  <h1>Hello World</h1>
</body>
</html>
Step 2

Review Validation Results

The validator instantly analyzes your HTML and provides detailed feedback on syntax, structure, accessibility, and best practices.

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Syntax validation: Checks for proper HTML syntax and structure
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Error reporting: Detailed error messages identifying specific issues
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Accessibility warnings: Alerts for missing alt attributes and best practice violations
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Document statistics: Information about elements, attributes, and structure depth

Common HTML Issues Detected:

❌ Unclosed tags: Missing closing tags for elements

<div><p>Text</div> // Missing </p>

⚠️ Missing alt attributes: Images without alt text for accessibility

<img src="photo.jpg"> // Should have alt="..."

⚠️ Self-closing tags: HTML tags that should use XHTML syntax

<br> // Consider using <br />
Step 3

Fix Issues and Download

If validation errors or warnings are found, use the detailed feedback to fix issues. Once validated, download your improved HTML document.

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Issue identification: Clear descriptions of what needs to be fixed
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Helpful warnings: Best practice recommendations for better HTML
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Real-time validation: Instant feedback as you make corrections
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Download option: Save your validated HTML file

Frequently Asked Questions

What does HTML validation check for?

HTML validation checks for syntax errors, well-formedness, proper tag nesting, attribute formatting, missing accessibility features (like alt attributes on images), self-closing tag issues, and compliance with HTML standards (HTML5 and legacy HTML).

Does this validator support HTML5?

Yes! The validator fully supports HTML5 and also works with legacy HTML versions. It validates modern HTML5 semantic elements, attributes, and document structures while also checking older HTML formats.

What are the accessibility warnings about?

Accessibility warnings alert you to issues that may affect users with disabilities, such as missing alt attributes on images or improper use of semantic HTML. These warnings help ensure your web pages are accessible to all users and comply with WCAG guidelines.

Can I validate HTML email templates with this tool?

Yes! This validator works great for HTML email templates. It will check syntax, structure, and provide warnings about potential issues. However, keep in mind that email HTML has different requirements than web HTML due to email client limitations.

How is this different from the W3C HTML Validator?

While the W3C validator is comprehensive and checks against formal specifications, our validator focuses on quick, practical validation with instant feedback, accessibility warnings, and a user-friendly interface. It's perfect for rapid development and testing.

Is my HTML code sent to any server?

No! All validation happens entirely in your browser using client-side JavaScript. Your HTML code never leaves your computer, ensuring complete privacy and security for your sensitive code or proprietary templates.

Can this validator fix my HTML errors automatically?

The validator identifies and reports errors but doesn't automatically fix them. However, it provides detailed error messages and warnings that guide you in making the necessary corrections. For automatic formatting, check out our HTML Formatter tool.

Is this HTML validator completely free?

Yes, completely free with no file size limits, no registration required, and unlimited usage. All validation features, error reporting, and accessibility warnings are available at no cost.