HTML Validator

Validate HTML code for errors, warnings, and compliance with web standards

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15,088+

Total Calculations Run

< 15ms

Browser Execution Speed

100%

Client-Side Privacy

4.9 / 5.0

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About This Tool

Our HTML Validator tool helps developers and webmasters check HTML code for syntax errors, missing tags, accessibility issues, and W3C compliance. Simply upload an HTML file, paste your HTML code, or enter a URL to validate. The tool provides detailed error and warning messages with line numbers and suggestions for fixes. All validation happens client-side in your browser - no data is sent to external servers.

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How to Use

Choose your input method: Upload an HTML file, paste HTML code, or enter a URL
Click the 'Validate HTML' button to start validation
Review the detailed results showing errors, warnings, and compliance status
Fix issues in your code based on the suggestions provided

Frequently Asked Questions

Find Quick Answers

What types of HTML errors does this validator detect?

The validator detects syntax errors, missing or mismatched tags, deprecated elements, accessibility issues (missing alt attributes, improper heading structure), and non-compliant code that violates W3C standards.

Is my HTML code sent to external servers for validation?

No, all validation happens entirely in your browser using JavaScript. Your code never leaves your computer, ensuring complete privacy and security.

Can I validate HTML from a live website URL?

Yes, you can enter any public URL to validate the HTML of that webpage. The tool will fetch the HTML content and validate it locally in your browser.

Does this tool check for CSS or JavaScript errors?

No, this tool specifically validates HTML structure and syntax. It does not validate CSS or JavaScript code, though it may flag issues related to how those technologies interact with HTML.

Need to run multiple calculations?

Create a free account today to unlock unlimited daily runs, access advanced parameters, save your history, and request custom features.

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