HTML Validator is a simple tool to reveal parts of your HTML code that do not conform to
the HTML5 standard by the World Wide Web Consortium (W3C).
Over the years, web developers attempted to make their web sites better and easier to use for their visitors,
but quite often they faced technical issues of erratic behaviour of different browsers, badly designed or weak protocols,
that made them introduce number of hacks into their webs, which made the situation even worse in the long run.
Today, it is believed by many that the correct approach is to conform to standards that are designed to reflect
the needs of web developers as well as end users. Also the web browsers are more mature and their products
attempt to follow the standards as much as possible in order to make the web development easier.
HTML Validator strictly follows the HTML5 standard and validates the code of the target web pages – i.e. it informs you about
all problems in your code that are relevant to HTML5 standard. It is able to analyze multiple pages in a single run and thus speed up
the checking process. HTML validator reveals problems in the markup code, such as using unsupported or obsolete element attributes
or their values, using of nested elements in wrong order, having invalid or inconsistent meta information, syntax errors, etc.
Fixing the problems can help you to increase the end user experience for users across platforms. This is because if your HTML code
is not valid, it is not well-defined anymore, how the browser should render the web page. Visitors with different browsers can thus
see different design or content or might be unable to perform some actions on the target web page.
Our HTML Validator tool is based on The Nu Html Checker (v.Nu),
an open source HTML validation engine by W3C. Having a valid HTML code is not the only thing that a web developer should try to achive.
We also recommend to check the web for broken links and check the web site page load speed with the other tools that you can find in the See Also section above.
To run HTML Validator, fill in the target website's URL, set the Maximum pages to test,
and hit the "Check HTML Code!" button. Wait for the results and analyze them.
The Maximum pages to test sets the limit on how many pages can be crawled on the target website.
The tool can only test pages that are linked from the primary URL that you have entered.
The tool will fail if the target URL can't be accessed, or does not return a successful HTTP code.
The output report consists of a list of issues that were found in the HTML code of the target web pages.
Most of the problems are identified as errors, as they are in violation of the standard or W3C recommendations.
Those problems should be fixed as they can affect the end users experience. Small number of problems can be classified as warnings.
It is always better to fix those issues too, but at the moment they are not as serious as the problems classified as errors.
