Rank 579 in the Majestic Million · checked October 19, 2026
Does nejm.org block AI crawlers?
Yes, 5 of 17. As of October 19, 2026, nejm.org's robots.txt blocks GPTBot, ChatGPT-User, PerplexityBot, Google-Extended and CCBot from the whole site. It keeps the other 12 out of parts of the site. 5 of them are named in a group of their own; the others follow its rules for every crawler.
Its /llms.txt answered HTTP 403. The homepage answered HTTP 403 to ContextFetchBot, so there was nothing to measure.
Each crawler, by its robots.txt rules
From https://www.nejm.org/robots.txt (1,423 bytes, 14 user-agent groups), parsed per RFC 9309. Blocked: no path allowed. Partly blocked: some paths disallowed. The rule counts are those of the groups that apply.
| Crawler | Operator | Verdict | Rules that apply | Disallow rules | Allow rules |
|---|---|---|---|---|---|
| GPTBot | OpenAI | Blocked | Its own group | 1 | 0 |
| ChatGPT-User | OpenAI | Blocked | Its own group | 1 | 0 |
| OAI-SearchBot | OpenAI | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| ClaudeBot | Anthropic | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| Claude-User | Anthropic | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| Claude-SearchBot | Anthropic | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| anthropic-ai | Anthropic | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| PerplexityBot | Perplexity | Blocked | Its own group | 1 | 0 |
| Perplexity-User | Perplexity | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| Google-Extended | Blocked | Its own group | 1 | 0 | |
| Applebot-Extended | Apple | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| CCBot | Common Crawl | Blocked | Its own group | 1 | 0 |
| Bytespider | ByteDance | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| Amazonbot | Amazon | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| meta-externalagent | Meta | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| cohere-ai | Cohere | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| Diffbot | Diffbot | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
| ContextFetchBot (us) | ContextFetch | Partly blocked | Rules for all crawlers (*) | 12 | 7 |
Read nejm.org through ContextFetch
GET /r/ returns a page as Markdown, with X-Raw-Tokens and X-Output-Tokens headers. Add ?q= and a question to get only the passages that answer it. No key needed for 25 requests a day; a free key has 2,500 credits. nejm.org's robots.txt partly blocks ContextFetchBot: our index and crawls skip what it disallows, and a page you ask for is fetched once on your behalf (see the bot page).
curl -si "https://api.contextfetch.dev/r/https://nejm.org/"curl -X POST https://api.contextfetch.dev/v1/keys/freeHow ContextFetchBot behaves · All sites and the method · Raw data
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Your free key comes with 2,500 credits, no signup. One credit reads one page.