The debate over whether valid HTML is a ranking factor for Google Search has once again come to the forefront, with comments from experts such as John Mueller and frontend engineers like Jens Oliver Meiert. The heart of the discussion lies in how important valid HTML is for search engine optimization (SEO) and whether it plays a direct role in how websites rank on Google.

Valid HTML: A Foundation, But Not a Ranking Factor?

John Mueller, a Senior Search Analyst at Google, frequently addresses questions about technical aspects of SEO, including the role of valid HTML. In a recent discussion, Mueller clarified that valid HTML is not a direct ranking factor in Google’s search algorithms. “Google also doesn’t use typos as a ranking factor,” he explained, drawing a parallel to how HTML errors are handled. However, he stressed that ensuring valid HTML is still a professional standard for web development, just as producing content free from typos is essential for professional writers.

Mueller pointed out that while valid HTML might not directly impact ranking, its importance shouldn’t be underestimated. “Imagine you ship multiple typos on your homepage? Eww,” he commented, illustrating how poor-quality code, like errors in HTML, can degrade the user experience.

The Real-World Application: Is It Ignored by Top Websites?

Jens Oliver Meiert, a frontend engineering leader and tech author, conducted an annual analysis on HTML conformance for 200 of the world’s most popular websites. His findings are somewhat surprising: in 2024, only 0.5% of these top websites used fully valid HTML. The majority of websites—199 out of 200—contained some form of HTML error. According to Meiert, the errors ranged from minor issues like missing attributes in image tags to more significant structural problems.

Yet, despite the prevalence of HTML errors, many of these websites still rank highly in search results, confirming that HTML validity alone is not a ranking factor. As Meiert points out, “The point of this annual analysis is to check on full HTML conformance… not whether or not they rank well.” This underscores the broader message: while valid HTML is a marker of professional development, its absence does not necessarily correlate with poor rankings in Google Search.

User Experience and Accessibility: The Indirect Benefits

Where valid HTML does make an impact is in the overall user experience and accessibility of a site. Poorly structured HTML can lead to rendering issues across different browsers and devices, hurting the usability of a website. This can, in turn, affect metrics like bounce rates and time-on-page—factors that are indirectly tied to rankings.

One of the more significant concerns with invalid HTML is how it interacts with assistive technologies, such as screen readers. Improperly structured HTML can make it difficult for these devices to parse and convey the content of a website, which in turn impacts a site’s accessibility score—something that may influence both user satisfaction and, eventually, SEO outcomes.

As Mueller noted, “It’s trivial to validate the HTML that a site produces. It’s trivial to monitor the validity of important pages—like your homepage.” Ignoring this step in development may not cause an immediate drop in rankings, but it could gradually hurt a site’s performance as user engagement metrics suffer.

Valid HTML: Best Practice or Requirement?

Despite the fact that valid HTML is not a formal ranking factor, it’s clear that adhering to web standards remains a best practice. As Jens Oliver Meiert put it, “Professional web developers write valid HTML,” making it an essential baseline for maintaining quality, functionality, and user trust. However, the data shows that even industry-leading websites frequently contain HTML errors.

In summary, while valid HTML does not have a direct impact on rankings, it should not be disregarded. Maintaining clean, functional HTML improves user experience, accessibility, and site performance—all of which contribute indirectly to a site’s success in search results. As Mueller concluded, the absence of valid HTML is not a deal-breaker for Google rankings, but fixing these issues reflects a higher standard of web development professionalism.