Many Top Sites Have Invalid HTML And Still Rank

A recent discussion on Google’s Search Off the Record podcast challenges long-held assumptions about technical SEO, revealing that most top-ranking websites don’t use valid HTML.

Despite these imperfections, they continue to rank well in search results.

Search Advocate John Mueller and Developer Relations Engineer Martin Splitt referenced a study by former Google webmaster Jens Meiert, which found that only one homepage among the top 200 websites passed HTML validation tests.

Mueller highlighted:

“0.5% of the top 200 websites have valid HTML on their homepage. One site had valid HTML. That’s it.”

He described the result as “crazy,” noting that the study surprised even developers who take pride in clean code.

Mueller added:

“Search engines have to deal with whatever broken HTML is out there. It doesn’t have to be perfect, it’ll still work.”

When HTML Errors Matter

While most HTML issues are tolerated, certain technical elements, such as metadata, must be correctly implemented.

Splitt said:

“If something is written in a way that isn’t HTML compliant, then the browser will make assumptions.”

That usually works fine for visible content, but can fail “catastrophically” when it comes to elements that search engines rely on.

Mueller said:

“If [metadata] breaks, then it’s probably not going to do anything in your favor.”

SEO Is Not A Technical Checklist

Google also challenged the notion that SEO is a box-ticking exercise for developers.

Mueller said:

“Sometimes SEO is also not so much about purely technical things that you do, but also kind of a mindset.”

Splitt said:

“Am I using the terminology that my potential customers would use? And do I have the answers to the things that they will ask?”

Naming things appropriately, he said, is one of the most overlooked SEO skills and often more important than technical precision.

Core Web Vitals and JavaScript

Two recurring sources of confusion, Core Web Vitals and JavaScript, were also addressed.

Core Web Vitals

The podcast hosts reiterated that good Core Web Vitals scores don’t guarantee better rankings.

Mueller said:

“Core Web Vitals is not the solution to everything.”

Mueller added:

“Developers love scores… it feels like ‘oh I should like maybe go from 85 to 87 and then I will rank first,’ but there’s a lot more involved.”

JavaScript

On the topic of JavaScript, Splitt said that while Google can process it, implementation still matters.

Splitt said:

“If the content that you care about is showing up in the rendered HTML, you’ll be fine generally speaking.”

Splitt added:

“Use JavaScript responsibly and don’t use it for everything.”

Misuse can still create problems for indexing and rendering, especially if assumptions are made without testing.

What This Means

The key takeaway from the podcast is that technical perfection isn’t 100% necessary for SEO success.

While critical elements like metadata must function correctly, the vast majority of HTML validation errors won’t prevent ranking.

As a result, developers and marketers should be cautious about overinvesting in code validation at the expense of content quality and search intent alignment.

Listen to the full podcast episode below: