errorLine 1, column 1
Parser reported missing doctype.
Review the reported area and close or reorder tags as needed.
HTML Tools
HTML Validator
Validate HTML for unsafe markup, duplicate IDs, and common quality issues.
Quick answer
Check HTML for unsafe markup, duplicate IDs, broken structure, and other practical issues before you publish.
EN
Invalid
CHECK
Errors
4
Warnings
1
error
Inline event handler "onclick" detected.
Remove inline JavaScript handlers from the markup.
error
Unsafe <script> tag detected.
Remove executable or embedded content before publishing.
warning
Link opens in a new tab without rel="noopener noreferrer".
Add rel="noopener noreferrer" for security.
error
Unsafe URL detected in "href".
Use safe http, https, mailto or relative URLs instead.
Overview
This HTML validator helps you catch common markup problems fast. It is useful for checking unsafe elements, duplicate IDs, invalid nesting, missing attributes, and quality issues that can affect accessibility, SEO, and rendering. The tool runs client-side, so your HTML stays in your browser.
Use cases
- Validate page templates before deployment.
- Check CMS content for unsafe or messy markup.
- Find duplicate IDs that can break scripts and accessibility.
- Review HTML copied from editors, emails, or page builders.
- Spot missing alt text, empty links, and other quality issues.
How it works
- 1
Paste your HTML into the input box.
- 2
Run validation to scan tags, attributes, structure, and IDs.
- 3
Review errors, warnings, and safe output details.
- 4
Fix the issues and validate again until the HTML is clean.
Examples
Basic validation
Input: <div id="hero"><a href="#">Read more</a></div>
Output: Reports structure and quality checks for the supplied HTML.
Use this for a quick check of simple markup.
Unsafe markup scan
Input: <script>alert('x')</script><p>Text</p>
Output: Flags unsafe elements and potential security risks.
Helps you catch code that should not be published.
FAQ
Does this tool change my HTML?
No. It only analyzes the HTML and reports issues, warnings, and validation details.
Can it detect unsafe markup?
Yes. It checks for risky tags and patterns that may be unsafe in published content.
Does it find duplicate IDs?
Yes. Duplicate IDs are reported because they can break anchors, scripts, and accessibility.
Is the validation done in the browser?
Yes. The tool is designed for client-side use and does not need an external API.