Whether you’re a frontend developer, lead, or manager, reconsider your expectations and practices if you haven’t yet chosen not to ship erroneous HTML. The more of us decide to talk about using actual HTML on our sites and in our apps, and lead by example, the better for our users and clients, and the better for our craft and profession. On the engineering side of web development, it’s HTML first—if it is HTML. - Source: dev.to / 2 days ago

Validate Your Code Include tools like W3C code validation service and CSS validator to ensure your code meets web standards. - Source: dev.to / 2 months ago

===> Click here to run your code through the HTML validator. - Source: dev.to / 5 months ago

Try looking at tools like https://validator.w3.org/. Source: 6 months ago

I'm looking for either that specific validator (older version of https://validator.w3.org/) or an equivalent that can validate pre-HTML5 (DTD-based) files in a similar fashion. I would appreciate any pointers in the right direction. Thanks in advance. Source: 11 months ago

The W3C website is a great resource, the section on ARIA](https://www.w3.org/WAI/ARIA/apg/) and as others have pointed out the patterns section is great and includes examples. Source: about 1 year ago

I copied that directly into the validator at w3.org and it showed no errors. https://validator.w3.org/nu is what you're using, yes? Source: over 1 year ago

Time to start Googling! Those are all solvable things that you can fix. The last ones in black are strange though... I have no idea what the reference to w3.org is for. Source: over 1 year ago

Google tells me some pages on my website have mobile usability errors - detailed results on GSC show 45 of 75 resources couldn't be loaded, many are apparently script and stylesheet issues to do with the theme and some plugins. The affected pages also load very slowly on GTMetrix. I turned on minify html, css and js on my caching plugin but it didn't seem to help. I did a Validate CSS check using a tool on w3.org... Source: over 1 year ago

Depending on what prompted this issue, there are a myriad of resolutions. If it's your SSL certificate then you simply need to get that registered and compliant. If it's because of bad coding then you can check out https://w3.org to test your code and fix it. Otherwise, you could always hire or consult a web developer. Source: over 1 year ago