AI crawlers in robots.txt: a study of the top 10k sites (2026)
Comments on “AI crawlers in robots.txt: a study of the top 10k sites (2026)”
Claim-checked. Scored by all three judges, and its checkable claims were compared with the sources it cites. How far stories are checked
HitMind analyzed robots.txt files from the top 10,000 domains and found that 329 of 1,105 files (29.8%) that block paths for everyone while naming an AI crawler let that crawler past at least one block. Under RFC 9309, a crawler with its own group ignores the * rules, so a bare Allow: / for GPTBot reopens search, account and API paths. About a fifth of domains refused the crawler, and the study measures rules, not what crawlers actually fetched.
Why it ranked
No. 10 of 110 with a score of 0.67. The panel rated it highest on new information (0.91) and substantiated (0.91), lowest on significance (0.55). Placed No. 10, No. 16 by score alone: the placement terms moved other stories past it.
- AI judgeJudge 2claude-haiku-5-5
- Original large-scale measurement of AI crawler rules in robots.txt with a practical robots.txt inheritance gotcha and fix. Well-substantiated with data and method; some promotional tool plugs.
- AI judgeJudge 3gpt-5.6-luna
- A detailed, reproducible measurement of robots.txt behavior across 10,000 domains, with methodology, denominators, limitations, and practical implications. It includes useful tools but is primarily substantive original research rather than marketing.
Each judge wrote its line after answering the rubric, with the site and the author still hidden. Every answer behind this is in the table under Score.
Score
0.67total under rubric v2.3
- Significance0.55
- Reader interest0.75
- Audience breadth0.64
- Practical relevance0.81
- Substantiated0.91
- Technical depth0.82
- New information0.91
- Counts against: Promotional0.20
- Counts against: Overclaim0.14
Each judge’s answer per question (0–1), their mean and spread, and what the question adds to the score (weight × mean).
| Question | Judge 1 | Judge 2 | Judge 3 | Mean | Spread | Weight | Contribution (weight times mean) |
|---|---|---|---|---|---|---|---|
| SignificanceHow much does this change what people in tech know or can do? | 0.59 | 0.40 | 0.65 | 0.55 | 0.25 | +0.24 | +0.131 |
| Reader interestWould a well-informed senior engineer or tech founder want to read this today, and likely pass it on? | 0.76 | 0.60 | 0.88 | 0.75 | 0.28 | +0.26 | +0.194 |
| Audience breadthHow many people who build technology does it concern? | 0.66 | 0.55 | 0.72 | 0.64 | 0.17 | +0.13 | +0.084 |
| Practical relevanceHow useful is it to someone who builds software or tech products? | 0.91 | 0.75 | 0.78 | 0.81 | 0.16 | +0.22 | +0.179 |
| SubstantiatedHow well is it backed? Consider whether it is the primary source, and whether its main claims come with data, code, a demo, a reproducible method or citations. | 0.99 | 0.80 | 0.93 | 0.91 | 0.19 | +0.05 | +0.045 |
| Technical depthHow technically substantive is it? | 0.97 | 0.70 | 0.78 | 0.82 | 0.27 | +0.05 | +0.041 |
| New informationDoes it contain information absent from the stories covered in the last 7 days (list provided)? | 0.91 | 0.85 | 0.97 | 0.91 | 0.12 | +0.05 | +0.046 |
| PromotionalIs it mainly marketing with little substance (a press release, ad or sponsored post with no real information)? A launch post that carries real news is not promotional. | 0.06 | 0.35 | 0.18 | 0.20 | 0.29 | −0.19 | −0.037 |
| OverclaimDo the headline or conclusions claim more than the body supports? | 0.16 | 0.20 | 0.06 | 0.14 | 0.14 | −0.11 | −0.015 |
| Sum of contributions | +0.667 | ||||||
| Claim-check penalty | 0.000 | ||||||
| Total, as published | 0.667 | ||||||
Spread is the highest minus the lowest judge answer. marks a spread above 0.40: the judges disagree, and the story is marked contested.
The badge for this ranking, for the author's page or anyone's: one line of HTML, and it links back here.
<a href="https://rubric.hrih.si/editions/2026-10-29/10/"><img src="https://rubric.hrih.si/badge/2026-10-29/10.svg" alt="Ranked #10 on Rubric, 29 Oct 2026" width="245" height="28"></a>Claim check
Claim check: 7 matches source · 1 couldn’t check. Each claim is compared with the source the article itself cites; a flag is published only when both checkers agree.
Matches sourceNumber
29.8% of robots.txt files that block paths for everyone and name an AI crawler let that crawler past at least one of those blocks (329 of 1,105).
The cited source says the same thing.
The article says “29.8% of the robots.txt files that block paths for everyone and name an AI crawler let that crawler past at least one of those blocks (329 of 1,105”
The source says “inheritance_gap,files_with_gap,329,1105,29.8,files that name an AI crawler and disallow paths under User-agent”
Source cited by the article: hitmind.ai/research/ai-crawler-access-2026/hitmind-ai-crawler-access-2026.csv
Matches sourceCausal conclusion
Under RFC 9309, a crawler obeys the User-agent: * group only if no group matches it, so a group naming GPTBot makes GPTBot ignore the * rules.
The cited source says the same thing.
The article says “So the moment a file adds a group for GPTBot — even one that only says Allow: / to welcome it — GPTBot stops reading every rule written under User-agent”
The source says “If no matching group exists, crawlers MUST obey the group with a user-agent line with the "*" value, if present”
Source cited by the article: rfc-editor.org/rfc/rfc9309.html
Matches sourceGeneralization
Google documents that user-agent-specific groups and the global * group are not combined for its crawlers.
The cited source says the same thing.
The article says “Google documents the same thing for its own crawlers: user agent specific groups and the global * group are not combined”
The source says “Ni los grupos específicos de user-agents ni los grupos globales (*) se unifican”
Source cited by the article: developers.google.com/search/docs/crawling-indexing/robots/robots_txt
Matches sourceNumber
GPTBot is blocked from the whole site by 14.8% of parseable robots.txt files, and by 21.6% among the top 1,000 domains.
The cited source says the same thing.
The article says “GPTBot is blocked from the whole site by 14.8% (21.6% among the top 1,000 domains”
The source says “crawler_blocked_sitewide,GPTBot,820,5539,14.8,parseable robots.txt files”
Source cited by the article: hitmind.ai/research/ai-crawler-access-2026/hitmind-ai-crawler-access-2026.csv
Matches sourceNumber
Only 7.1% of robots.txt files block at least one AI training crawler while leaving all 9 AI answer engines open.
The cited source says the same thing.
The article says “20.0% block at least one AI training crawler, but only 7.1% do so while leaving all 9 AI answer engines open”
The source says “training_vs_answer,training_only_block,392,5539,7.1,parseable robots.txt files”
Source cited by the article: hitmind.ai/research/ai-crawler-access-2026/hitmind-ai-crawler-access-2026.csv
Matches sourceNumber
14.4% of the sites that answered (878 of 6,082) serve a valid llms.txt.
The cited source says the same thing.
The article says “878 of the 6,082 sites that answered our request (14.4%) serve a valid one”
The source says “llms_txt,valid,878,6082,14.4,"sites that answered /llms.txt (excludes 403, 429, 5xx, network errors”
Source cited by the article: hitmind.ai/research/ai-crawler-access-2026/hitmind-ai-crawler-access-2026.csv
Couldn’t checkDate
llms.txt was proposed in September 2024.
The source was unreachable, paywalled or too long, or the two checkers disagreed.
The article says “proposed in September 2024”
The source says No passage could be compared.
Source cited by the article: llmstxt.org
Matches sourceNumber
Cloudflare published Content Signals in September 2025; 150 of 5,539 robots.txt files (2.7%) carry a Content-Signal line, and 90 of those say ai-train=no.
The cited source says the same thing.
The article says “150 of the 5,539 files (2.7%) carry one, and 90 of those say ai-train=no”
The source says “other_robots_lines,content_signal,150,5539,2.7,parseable robots.txt files”
Source cited by the article: hitmind.ai/research/ai-crawler-access-2026/hitmind-ai-crawler-access-2026.csv
Also covered by
No other coverage was clustered with this story.
Elsewhere
Elsewhere: HN 1 pts, not on front page
Recorded for context only, checked 29 Oct 2026, 05:47 UTC. It played no part in the ranking.