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What's the best HTML validator?

A commercial recommendation prompt. We size how many people ask ChatGPT this from real search demand, then run it through ChatGPT to see which websites it recommends.

Est. people asking / mo
2.8K
CPC
$2.03
Total est. value / mo
$270
Common ways people ask this (12)
  • What's the best HTML validator for beginners?
  • What's the best HTML validator for professional developers?
  • What's the best HTML validator for websites?
  • What's the best HTML validator for checking HTML5?
  • What's the best HTML validator for batch validation?
  • What's the best HTML validator for live code checking?
  • What's the best HTML validator for offline use?
  • What's the best HTML validator for browser-based use?
  • What's the best HTML validator for command line use?
  • What's the best HTML validator for accessibility checking?
  • What's the best HTML validator for SEO audits?
  • What's the best HTML validator on a budget?

What ChatGPT actually answered

The 5 times we asked ChatGPT this, each answer verbatim. The leaderboard below aggregates all 5 runs.

You: What's the best HTML validator?
ChatGPT:
  1. validator.w3.org
  2. html-validator.org
  3. validator.nu
  4. w3.org
  5. google.com
  6. stackoverflow.com
  7. developer.mozilla.org
  8. github.com
  9. npmjs.com
  10. cdnjs.cloudflare.com
  11. whatwg.org
  12. w3schools.com
  13. sitechecker.pro
  14. seositecheckup.com
  15. smallseotools.com
  16. dareboost.com
  17. browserling.com
  18. freeformatter.com

Websites ChatGPT recommends for this prompt

Aggregated across 5 runs (min 2/5 appearances). Estimated visits split the prompt's demand by rank. Sites matching the prompt's own brand are marked branded and excluded from the leaderboard.

Arrows show each site's rank change since Jul 2026.

RankWebsiteEst. visits / mo
1 validator.w3.org 56
2 w3.org 33
3 validator.nu brand 22
4 html5.validator.nu brand 15
5 developer.mozilla.org 11
6 stackoverflow.com 8
7 ▲1 github.com 6
8 ▲11 sitechecker.pro 5
9 ▼2 freeformatter.com 4
10 ▲1 browserling.com 3
11 new htmlvalidator.com 2
12 new smallseotools.com 2
13 ▲2 w3schools.com 1
14 ▼4 codebeautify.org 1
15 ▼1 seositecheckup.com 1
16 ▼7 whatwg.org 1
How is this estimated?

ChatGPT doesn't publish prompts, so we don't show logged conversations. We measure real demand for this topic from Google search volume, scale it to ChatGPT's user base (on average about 1 ChatGPT user for every 8 Google searchers, a ratio that varies by topic), and run the prompt through ChatGPT 5 times to record which websites it recommends and in what order. Estimated visits split that demand across the recommended sites by a click-through-by-rank curve. Every number is a modeled estimate, not measured analytics. Full methodology →