Are HTML standards and guidelines followed on the Internet?
Posted: Sun Jan 26, 2025 3:25 am
This is the question I asked myself when I discovered that 0 of the top 100 websites in the world comply with HTML and CSS standards.
Sergio Vergara
Sergio Vergara
November 7, 2023 — 2 minutes reading time
Are HTML standards and guidelines followed on the Internet?
Photo by Florian Olivo on Unsplash
None of the top 100 most visited websites worldwide use fully standards-validated HTML, according to the HTML specifications.
Based on Ahrefs' annual Top 100 Websites update , effective venezuela mobile numbers list Jens Oliver from Meiert.com has performed a check on the HTML standards validity of the homepages of these websites.
The following data gives us an approximation of how the W3C web standards are being implemented on the Internet. The objective of this analysis is to check the overall validation of HTML and CSS validation checks, expecting an absence of errors on the most important websites on the Internet.
To do this, the HTML and CSS validation has been reviewed, documenting the total error count. You can consult the complete list of websites here . Below you can see the result of the first 20 websites:
Top 100 Websites Compliance Data Spreadsheet Preview
Most visited websites and their use of HTML and CSS according to specifications.
HTML Validation
It's surprising how in 2023, 0 out of 100 websites have 0 HTML validation errors. Only Adobe, Speedtest, and Spotify were very close to validation, with 1 error each. And 14 more had a reasonable number of errors, below 10. But 37 of these websites are far from meeting the specifications, with 100 or more errors. The average number of HTML errors is 132.14.
CSS Validation
The W3C CSS validator is in need of updating as there appear to be many false positives and probably some false negatives, raising concerns that the results are no longer practically useful. CSS validation is not as critical as HTML validation, but it is important to have a reliable CSS validator. 12 out of 94 websites tested have 0 CSS conformance errors. 34 were close to conformance, with an error count of less than 10. 7 were far off with 100 or more errors, and one site contained over 1000 errors. The average number of CSS errors is 46.79.
Sergio Vergara
Sergio Vergara
November 7, 2023 — 2 minutes reading time
Are HTML standards and guidelines followed on the Internet?
Photo by Florian Olivo on Unsplash
None of the top 100 most visited websites worldwide use fully standards-validated HTML, according to the HTML specifications.
Based on Ahrefs' annual Top 100 Websites update , effective venezuela mobile numbers list Jens Oliver from Meiert.com has performed a check on the HTML standards validity of the homepages of these websites.
The following data gives us an approximation of how the W3C web standards are being implemented on the Internet. The objective of this analysis is to check the overall validation of HTML and CSS validation checks, expecting an absence of errors on the most important websites on the Internet.
To do this, the HTML and CSS validation has been reviewed, documenting the total error count. You can consult the complete list of websites here . Below you can see the result of the first 20 websites:
Top 100 Websites Compliance Data Spreadsheet Preview
Most visited websites and their use of HTML and CSS according to specifications.
HTML Validation
It's surprising how in 2023, 0 out of 100 websites have 0 HTML validation errors. Only Adobe, Speedtest, and Spotify were very close to validation, with 1 error each. And 14 more had a reasonable number of errors, below 10. But 37 of these websites are far from meeting the specifications, with 100 or more errors. The average number of HTML errors is 132.14.
CSS Validation
The W3C CSS validator is in need of updating as there appear to be many false positives and probably some false negatives, raising concerns that the results are no longer practically useful. CSS validation is not as critical as HTML validation, but it is important to have a reliable CSS validator. 12 out of 94 websites tested have 0 CSS conformance errors. 34 were close to conformance, with an error count of less than 10. 7 were far off with 100 or more errors, and one site contained over 1000 errors. The average number of CSS errors is 46.79.