Free HTML Validator Tool
See how to use Free HTML Validator Tool
Depending on which input method you choose to use, pick a tab. You have the option to either validate by File Upload, Direct Input, or URL.
Once you have input the page you want validated, select which additional options you would like. Show outline will give you a machine generated outline of the page based on the headings. HTML Tidy will clean up the markup and give you the source code once the page has been “tidied up.” Verbose allows you to see longer error messages with more detail. Once you have input the page and picked the options, click on “Ninja Check” to see if your page validates or not.
The W3C Markup Validator powers this tool.