Tool Information
Our HTML Validator is an essential tool for ensuring that your website is accessible and renders correctly across all browsers, improving user experience. It allows you to check your HTML markup for compliance with W3C standards. The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Our validator makes it easy to check your HTML for errors, so you can be confident that your website is compliant with the latest standards and that it will be displayed correctly in all web browsers. The tool is designed to be fast and accurate, and it can validate any HTML markup. It provides you with clear and helpful error messages, so you can quickly identify and fix any issues in your HTML. By using our validator, you can save time and effort, and you can prevent errors that can arise from invalid HTML. Our HTML Validator is a must-have tool for any web developer. It is a simple yet powerful tool that can have a big impact on the quality of your website. By using our validator, you can create more accessible and user-friendly websites, and you can ensure that your content is available to the widest possible audience.
HTML Validator — Check Markup & Accessibility
Paste HTML markup and run quick validation checks for best practices, accessibility, and common issues.
alt, duplicate id, inline event handlers, and more.How to Use the HTML Validator
- Paste your HTML markup in the left editor.
- Click Validate to run quick checks for accessibility and common issues.
- Review the categorized issues (Errors, Warnings, Info) on the right panel.
- Copy or download the JSON report for CI or sharing with teammates.
What this validator checks
- • Presence of DOCTYPE and
langon <html>. - • Missing or empty <title> tag.
- • Images missing
altattributes (accessibility). - • Anchor target="_blank" missing rel security attributes.
- • Duplicate IDs, inline event handlers, deprecated tags, and large inline scripts/styles.
⚠️ Important: This is a quick, client-side checker for common issues. For full standard compliance and spec-level validation, use the W3C Validator or server-side linters.
💡 Pro Tip: Use this tool to catch accessibility and common markup issues early in development. Keep formatted source for development and use validated/minified output for production workflows.
What is an HTML Validator?
An HTML Validator is a tool that checks your HyperText Markup Language (HTML) code for syntax errors and compliance with web standards. It helps you find issues like unclosed tags, improper nesting of elements, and the use of deprecated attributes. Ensuring your HTML is valid is a crucial step in web development.
Why Use Our HTML Validator?
- Cross-Browser Compatibility: Valid HTML is more likely to be rendered consistently across different web browsers.
- Accessibility: Proper HTML structure is essential for assistive technologies like screen readers to interpret your content correctly.
- SEO: Search engines can better understand and index your content when it's well-structured and valid.
- Debugging: It's often the first step in debugging layout and styling issues, as invalid HTML can cause unexpected rendering problems.
🚀 Explore More Free Developer Tools
Don’t stop here! Supercharge your workflow with our other powerful converters & formatters.
✨ HTML Formatter
Format HTML code with proper indentation and tag structure
⚡️ HTML Minifier
Minify HTML by removing unnecessary whitespace and comments
🚀 Markdown to HTML
Convert Markdown text to HTML
💡 New tools are added regularly — bookmark DevUtilsX and stay ahead!
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