Reviews of Free Online HTML Code Validators
An HTML validator is a debugging tool that checks your HTML code to let you know if you have errors. It is set up to check if your site is in compliance with the World Wide Web Consortium of (W3C). If you are having a problem with the layout of your page it may be invalid or broken code that is the problem. It's always a good idea to check the page with a validator several times during the design process.
Why you should check your code with a HTML Validator?
If your site is set up for HTTPS and the validator throws an error see if it has an option for HTTPS.
If you don't check your HTML code it can cause some browsers to crash or not display your web page properly. Most importantly, search engine spiders may not be able to pick up the text off your page with broken HTML. The same goes for broken links on your website. Most search engine quidelines recommend that the HTML code validates. Google is also using quality of content as a factor in it's Panda algorithm and that includes clean code.
When using a validator be sure and use the correct url including the WWW or non-WWW, whichever your site is set up for, or the validator may not work correctly.
To complicate the validation problem most visual web editors, blogs, CMS or WYSIWYG programs, that allow you to design a website with no knowledge of HTML, often produce code that is outdated and therefore doesn't validate. They often have enormous code bloat besides. Even the newest versions may not be code compliant with the W3C, which regulates HTML code, so be sure and upgrade to the newest versions when they become available.
Code that links to your social networks may not validate. When that happens sometimes it helps to update the Doctype to HTML5.
If your website ranking has dropped then it might help to check your code with an HTML validator. If your website comes back in a few weeks then that was the problem. If not, look for other problems such as Website Hijacking or look to see if there are any Technology Blockers in your code. If neither of those solve your problem then you might check out my Manual SEO Audits page as I may be able to figure out what is causing your ranking to drop.
Reviews of HTML Code Validators and Error Checkers
The following reviews cover sites offering a free online HTML Code Validator. Not all of them provide the same service and some are more thorough than others. If a site is having severe problems I prefer to use the W3C validator first and then try other programs which catch broken tags or links that W3C can miss. Be aware that if you have upgraded your site to HTML5 that not all validators have been upgraded to that version of HTML. Downloadable HTML validators are not included below although there are add-ons for Firefox and Chrome that you might try.
The W3C HTML Validator Service checks HTML documents for conformance to W3C HTML and XHTML recommendations and other HTML standards. This one is not as user friendly for beginners as the others, however, it is the one more experienced web designers should use. You should have a doc type declaration and also character type in the meta tags before it will analyze the HTML code correctly.
The W3C HTML validator gives an explanation for each error it finds and also lets you check other markup codes like CSS Stylesheets, RSS feeds and a broken link checker. You can either upload your code or provide a URL. It lets you know what line the error occurred on and you can choose to have it show the source code and highlight the error.
If you have a missing end tag that one error can cause a cascade of other errors in your code, so check the validator again after fixing a broken tag.
HTML5 Closing Tag Checker Sometimes when using the validators above they will indicate you have a closing tag missing (like an end tag for a div or paragraph, etc.) If you're not able to find the missing tag check this validator as it might give you another clue as to what's wrong. You'll need to have the rest of your code validated first before using this program however.
The HTML Validator / Linter checks your code for W3C compliance. It can also find stray characters, duplicate ID tags, missing HTML tags, invalid attributes and other problems. It will let you know if your character set is out of date, HOWEVER it throws an error for character entities like the code for Registered or Trademarked items.
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