Validate html code

To be certain of a good representation of a homepage in different common browsers, it is necessary to validate the code.
4 answers

validate html code using online tool

And there is an online validator
http://validator.w3.org/

Validate html code

This is an other validator to checks the markup validity of Web documents in.
Enter adress and options to check.

http://htmlhelp.com/tools/validator/

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Offline Validator

There also exist offline-versions of validator tools like the "Total Validator Tool" that is available at http://www.totalvalidator.com/tool/index.html. With them you can check also sites that are on a non-public server or offline.

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Check the markup (HTML, XHTML, …) of Web documents

This validator checks the markup validity of Web documents in HTML, XHTML, SMIL, MathML, etc. This validator is part of Unicorn, W3C's unified validator service.
Enter adress and options to check.

http://validator.w3.org/