How to Try or Download CSS HTML Validator (and What It Runs On)

Updated

You can try CSS HTML Validator before paying: the site offers a free trial download, plus a permanently free "Limited Version." The main product is native Windows software with a GUI; Mac and Linux users get a separate console tool called htmlval. Everything runs locally on your own computer, so no internet connection is required during validation.

What you can actually download

Option Platform What it is Cost signal on site
Free trial Windows Full-featured trial of the Windows GUI product Free trial
Limited Version Windows Reduced-feature free edition FREE
Home edition Windows Full Windows product, home use $60 or less
Professional edition Windows Full Windows product, professional use $125 or less
htmlval Mac / Linux Console (command-line) tool $79

The site also lists a "Buy Upgrade" path for existing licenses, an academic license, and a classroom-use license, so schools and students have separate purchase routes rather than buying the standard edition.

System requirements and platform notes

  • Windows: This is the primary platform. The Windows build includes the GUI and is described as native software with "Native C++ Performance." The current release noted on the page is V26.02, with support stated as "Updated for 2027."
  • Mac and Linux: Supported through htmlval, a console tool. This is command-line only — you won't get the graphical editor or the full GUI workflow.
  • Chromebook, Mac, or Linux with the Windows GUI: The site states you can "Run on Chromebook, Mac, or Linux" and mentions Wine support for running the Windows software on other platforms. Treat this as a compatibility path rather than a native build.
  • PHP syntax checking: Requires Windows plus a free third-party download, and is listed as a Home+ feature. If PHP checking matters to you, plan for Windows.

How to get started

  1. Go to htmlvalidator.com and choose the download option for your platform — the Windows trial, or htmlval for Mac/Linux.
  2. Install and open the tool. On Windows you get the GUI; on Mac/Linux you run htmlval from a terminal.
  3. Point it at a page or file you want to check. The validator reports issues across HTML/HTML5, CSS, accessibility, SEO, links, spelling, JavaScript linting, and mobility (Android/iOS) checks.
  4. Review the flagged problems and fix them in your source. Because the tool runs offline, your documents never leave your machine — useful if you're checking client work or internal pages.

What to know before you buy

  • No subscription. The page states "No Subscription" and "No recurring subscription fees," so the listed prices are one-time license costs rather than monthly charges.
  • 30-day money-back guarantee. The site backs the product with a refund window, which lowers the risk of buying the wrong edition.
  • Priority maintenance and support is sold as a separate item, so ongoing support is not automatically bundled with every license.
  • Editions differ by feature, not just price. PHP checking, for example, is tied to Home and above. Compare editions on the site before choosing, especially if you need PHP or the GUI editor.

Common sticking points

  • Expecting a native Mac GUI. Mac and Linux get htmlval, a console tool — if you want the graphical interface, you're on Windows or running the Windows build through Wine.
  • Assuming the free option is the full product. The Limited Version is a reduced free edition; the trial is the way to evaluate full functionality.
  • Forgetting the PHP dependency. PHP syntax checking needs Windows and an extra free download, so it isn't available out of the box on Mac/Linux.