Input example
<article><h1>Title</h1><p>Text</p></article>HTML tool
Validate HTML Online
Check whether HTML can be parsed by the browser. No signup is required.
Open toolBrowser tool
Paste or upload content
The input is processed locally in your browser. You can copy, download, or share the result.
Paste or upload content, then run the tool.
When to use this HTML validator
Use this HTML check before sharing snippets, testing copied markup, or comparing two versions of a small page section. It is designed for everyday web, data, and developer workflows where a quick browser-side result is more convenient than opening a heavy desktop application.
The best workflow is to paste a small representative sample first, confirm the output looks correct, and then process the full content if it is appropriate to handle in your browser.
Example
Validate HTML Online example
Use this before-and-after sample as a quick reference for what the tool changes.
Output example
HTML looks valid.Review checklist
Common mistakes to avoid
Unclosed tags inside nested markup
Review this point before copying the output into another system, committing it to a project, or sending it to someone else.
Attributes with missing quotes
Review this point before copying the output into another system, committing it to a project, or sending it to someone else.
Expecting browser parsing to catch every accessibility or SEO issue
Review this point before copying the output into another system, committing it to a project, or sending it to someone else.
Privacy and local processing
This HTML validator runs in your browser. The page uses client-side JavaScript to process pasted text or uploaded files, and it does not require an account. Share links can include the content you entered, so only create or send a share link when the content is safe for the recipient to view.
For private projects, remove passwords, API keys, access tokens, personal information, customer records, and internal identifiers before using any online utility.
FAQ
Validate HTML Online FAQ
Does this tool upload my file?
The tool is designed to process content in your browser with client-side JavaScript. You should still avoid using sensitive files in any browser-based tool unless you are comfortable handling that data there.
Can I download the result?
Yes. After running the tool, use Download output to save the processed content as a local file.
Can I share the result?
Yes. Use Share link to copy a link containing the current input and output. Only share it with people who should see the content.