CSS HTML Validator: The All-In-One HTML, XHTML, CSS, Link, SEO, and Accessibility Checker
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FREE UPGRADE: Buy 2020/v20 now and automatically receive a FREE upgrade to 2021/v21 when available.
  • System Requirements: Microsoft Windows® 7, 8.1, or Windows 10
  • Validate up to 200 documents within 30 days with the trial version.
  • See what's new in the latest version.
  • The home edition is not available as a trial download. Instead, try the professional edition. The home edition is just like the professional edition minus a few features.
  • View the license agreement (EULA).
  • View the uninstall instructions.
  • Contact us if you have any problems or questions downloading.

Download CSS HTML Validator for Windows

Small CSS HTML Validator screenshot

Version 20.04 Version 20.04 is now available.

Download Trial Version (Pro)

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Download for Personal, Non-commercial Use (FREE)

CSS HTML Validator for Personal, Non-commercial Use is a FREE older version that is licensed only for personal, non-commercial use. Download this free version here.

After Downloading

After downloading, run the setup installer and answer Yes to the User Account Control prompt then follow the simple installation instructions. The setup program is digitally signed by AI Internet Solutions LLC (do not run it if it is not).

IMPORTANT: On some systems it may take 1 to 2 minutes for the User Account Control dialog to appear because the system is checking the file.

If the User Account Control dialog does not appear or you get an error message like "Error 5: Access is denied." then please try one or more of the following:

  • Run the setup program by right-clicking on it and choosing Run as administrator.
  • Temporarily disable any security software like anti-virus and anti-spyware (it may be preventing the setup program from running).
  • If problems persist then please see Known Issues with 3rd Party Software.

Download Dictionaries

Download Dictionaries

Additional dictionaries are available to support more languages.

A dictionary editing tool is also available. This tool lets you create your own custom dictionaries.