Easy Code Checking With Unicorn: the W3C’s Unified Validator

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As a SitePoint reader, you understand the importance of code validation. Even if you’re not a semantic shaman, fixing problems is far easier when you know your HTML and CSS is valid. There are many online and offline tools to help your validation efforts but you normally need to test HTML, CSS, and feeds separately. HTML5 validators are also in short supply. The W3C’s Unicorn project could save your sanity. It’s a unified system which aggregates results from several validators to produce a single mark-up report. It includes checks for:

  • HTML — including HTML4, XHTML and HTML5
  • CSS 1, 2, 2.1, and 3 (although it appears to default to 2.1)
  • SVG basic and tiny
  • mobile device ‘suitability’
  • feed checkers for formats including RSS and Atom
The tool can be used online at validator.w3.org/unicorn/ or you can download the open source Java code for offline usage.

Web Developer Toolbar integration

If you’re using the WDT extension for Firefox (not Chrome — sorry), you can add Unicorn as a validation tool. Open the WDT Options dialog and choose Tools
in the left-hand pane. Click Add then enter:
  • W3C Unicorn for the description
  • choose URL for the tool type, and
  • enter the URL http://validator.w3.org/unicorn/check?ucn_task=conformance&ucn_uri=
WDT options OK your way out and you should now find the Unicorn entry in your WDT Tools menu. Have you tried Unicorn? Did your site pass validation? Will you use the tool regularly?

Frequently Asked Questions (FAQs) about W3C Unicorn Validator

What is the W3C Unicorn Validator?

The W3C Unicorn Validator is a comprehensive tool developed by the World Wide Web Consortium (W3C) to check the compliance of web pages with various web standards. It combines several testing tools into one, allowing users to validate HTML, CSS, and other web technologies in a single step. This makes it a convenient and efficient tool for web developers and designers to ensure their websites are up to standard.

How does the W3C Unicorn Validator work?

The W3C Unicorn Validator works by analyzing the source code of a web page. It checks the code against the specifications of various web standards, such as HTML, CSS, and accessibility guidelines. If it finds any discrepancies or errors, it provides detailed feedback, helping developers to identify and fix the issues.

Why should I use the W3C Unicorn Validator?

Using the W3C Unicorn Validator ensures that your website is accessible, user-friendly, and compatible with different browsers and devices. It helps to identify and fix coding errors that could affect the performance and functionality of your website. Moreover, adhering to web standards can improve your website’s search engine ranking.

How can I use the W3C Unicorn Validator?

To use the W3C Unicorn Validator, simply enter the URL of the web page you want to check in the input field on the Unicorn Validator’s homepage. Then, click the “Check” button. The tool will then analyze your page and provide a detailed report of any issues it finds.

What are the limitations of the W3C Unicorn Validator?

While the W3C Unicorn Validator is a powerful tool, it does have some limitations. For instance, it can only check public web pages, not those behind a login or on a private network. Also, it may not detect all types of coding errors, especially those related to newer web technologies.

Can the W3C Unicorn Validator check mobile compatibility?

Yes, the W3C Unicorn Validator can check mobile compatibility. It uses the MobileOK Checker, a tool developed by W3C, to assess the mobile-friendliness of a web page.

What is the difference between the W3C Unicorn Validator and other validation tools?

The main difference is that the W3C Unicorn Validator combines several validation tools into one, making it a one-stop solution for checking web standards compliance. Other tools may only check for specific standards, requiring you to use multiple tools to fully validate a web page.

Is the W3C Unicorn Validator free to use?

Yes, the W3C Unicorn Validator is a free tool. It is part of W3C’s mission to promote the adoption of web standards, and as such, it is freely available for anyone to use.

Can I use the W3C Unicorn Validator to check my website’s SEO?

While the W3C Unicorn Validator can help improve your website’s SEO by ensuring it adheres to web standards, it is not a dedicated SEO tool. It does not provide specific SEO recommendations or keyword analysis.

What should I do if the W3C Unicorn Validator finds errors in my web page?

If the W3C Unicorn Validator finds errors, it will provide a detailed report, including the line numbers where the errors occur. You should review this report and make the necessary corrections to your code. If you’re unsure how to fix an error, consider seeking help from a web development professional or community.

Craig BucklerCraig Buckler
View Author

Craig is a freelance UK web consultant who built his first page for IE2.0 in 1995. Since that time he's been advocating standards, accessibility, and best-practice HTML5 techniques. He's created enterprise specifications, websites and online applications for companies and organisations including the UK Parliament, the European Parliament, the Department of Energy & Climate Change, Microsoft, and more. He's written more than 1,000 articles for SitePoint and you can find him @craigbuckler.

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