Safe Official docs AI & LLM Bots

Cloudflare Crawler (Browser Run)

Operated by Cloudflare

Quick Facts

User-Agent:
CloudflareBrowserRenderingCrawler
Category:
AI & LLM Bots
Operator:
Cloudflare
Safety:
Safe
Blocking Impact:
Low - No effect on Google or Bing rankings
SEO Impact Score:
1/10
Official docs:
developers.cloudflare.com

Confirmed by the operator

Cloudflare names CloudflareBrowserRenderingCrawler on its own documentation page, linked above. The token, purpose and robots.txt behaviour on this profile come from that page, re-checked on October 19, 2026.

What is Cloudflare Crawler (Browser Run)?

CloudflareBrowserRenderingCrawler is the user agent of the /crawl endpoint in Cloudflare Browser Run, which Cloudflare customers use to crawl websites.

It identifies itself with the token CloudflareBrowserRenderingCrawler. Cloudflare documents it at developers.cloudflare.com.

What happens if you block Cloudflare Crawler (Browser Run)?

Blocking it stops Cloudflare customers crawling your site through Browser Run /crawl. It has no effect on Google or Bing.
Allow it unless you do not want Cloudflare customers crawling your site through Browser Run.

Want to see whether Cloudflare Crawler (Browser Run) actually visits you? Read how do I monitor AI bot traffic to my website?

How to block Cloudflare Crawler (Browser Run) with robots.txt

<code>User-agent: CloudflareBrowserRenderingCrawler</code> - Matching is case-insensitive. Robots.txt is fetched from the root of each subdomain separately.

Block completely (robots.txt)
User-agent: CloudflareBrowserRenderingCrawler Disallow: /
Allow all (robots.txt)
User-agent: CloudflareBrowserRenderingCrawler Allow: /
Block private only (robots.txt)
User-agent: CloudflareBrowserRenderingCrawler Disallow: /private/ Disallow: /api/ Disallow: /admin/ Allow: /
Nginx server block
# Nginx: Hard-block Cloudflare Crawler (Browser Run) if ($http_user_agent ~* "CloudflareBrowserRenderingCrawler") { return 403 "Bot blocked"; }
Apache .htaccess
# Apache: Hard-block Cloudflare Crawler (Browser Run) SetEnvIfNoCase User-Agent "CloudflareBrowserRenderingCrawler" bad_bot Order Allow,Deny Allow from all Deny from env=bad_bot
Meta robots tag
<meta name="robots" content="noindex, nofollow">
X-Robots-Tag header
X-Robots-Tag: noindex, nofollow

Is Cloudflare Crawler (Browser Run) safe to allow?

Yes. Cloudflare Crawler (Browser Run) is a documented bot: Cloudflare publishes a page that names it and explains what it does.
Cloudflare says Browser Run requests carry signature headers that point at Cloudflare's bot verification keys. Use the bot detection IDs Cloudflare publishes for WAF rules.

What does Cloudflare Crawler (Browser Run) do?

From Cloudflare's own documentation.

  • CloudflareBrowserRenderingCrawler is the user agent of the /crawl endpoint in Cloudflare Browser Run, which Cloudflare customers use to crawl websites.
  • Blocking it stops Cloudflare customers crawling your site through Browser Run /crawl. It has no effect on Google or Bing.

Cloudflare Crawler (Browser Run) in context

Cloudflare Crawler (Browser Run) is a utility crawler operated by Cloudflare. In plain terms, it harvests pages for a dataset or data product. Our database files it under AI and LLM crawlers and ranks it Tier 3, mid-priority crawlers with a clear purpose but a smaller audience. 15 of the 104 AI and LLM crawlers in our database share this tier.

Its safety rating is safe and its blocking impact is low. So the decision about Cloudflare Crawler (Browser Run) rests on what you want from Cloudflare, not on its behaviour. How we rate safety and impact.

How site owners treat Cloudflare Crawler (Browser Run)

Our robots.txt study of the Tranco top 10,000 did not track CloudflareBrowserRenderingCrawler as a named token, so we do not publish an adoption figure for it. If you run a large site, your own logs are the best evidence of how often it visits.

Does it follow robots.txt?

Cloudflare Crawler (Browser Run)'s operator says it follows robots.txt, so a correctly written Cloudflare Crawler (Browser Run) group is enough to control it.

Cloudflare crawlers and close alternatives

Cloudflare Crawler (Browser Run) is one of 4 Cloudflare crawlers in our database. A User-agent: CloudflareBrowserRenderingCrawler group controls Cloudflare Crawler (Browser Run) only; the other Cloudflare tokens below need their own lines.

  • CloudflareBrowserRenderingCrawler: this crawler (Tier 3)
  • Cloudflare-AI-Search: Cloudflare AI Search, builds a search or answer index (Tier 2)
  • Cloudflare-AI-Search-External: Cloudflare AI Search (external sites), builds a search or answer index (Tier 3)
  • Cloudflare-AutoRAG: Cloudflare AutoRAG, builds a search or answer index (Tier 2)

To give Cloudflare Crawler (Browser Run) the same answer as its siblings, stack User-agent: CloudflareBrowserRenderingCrawler with their lines above one set of rules; to treat Cloudflare Crawler (Browser Run) differently, give it its own group.

Other AI and LLM crawlers that do the same job (harvests pages for a dataset or data product) include FirecrawlAgent from Firecrawl, iaskspider from iAsk, NovaAct from Amazon. Deciding about Cloudflare Crawler (Browser Run) is usually a decision about the whole group, so check how your file treats these too.

We first recorded CloudflareBrowserRenderingCrawler on October 19, 2026. Cloudflare documents it on developers.cloudflare.com, and we recheck that page before each release.

Which rule Cloudflare Crawler (Browser Run) actually follows

Cloudflare Crawler (Browser Run) reads exactly one group in robots.txt, the most specific one that names CloudflareBrowserRenderingCrawler, and never combines rules across groups. This short file shows the trap:

User-agent: *
Disallow: /private/

User-agent: CloudflareBrowserRenderingCrawler
Disallow: /drafts/
  1. Find the group. Cloudflare Crawler (Browser Run) looks for a group naming CloudflareBrowserRenderingCrawler. One exists, so it ignores User-agent: * completely.
  2. Apply only that group. It is refused /drafts/ and nothing else.
  3. The surprise. /private/ is open to Cloudflare Crawler (Browser Run), because that rule lives in the * group it no longer reads. To keep it out of both, repeat Disallow: /private/ inside its own group.
Test yourself: does a rule under User-agent: * apply to Cloudflare Crawler (Browser Run) if the file also has a User-agent: CloudflareBrowserRenderingCrawler group?

No. Once a group names it, Cloudflare Crawler (Browser Run) reads only that group. Put every rule you want it to follow inside its own group.

Test yourself: will blocking Cloudflare Crawler (Browser Run) remove your pages from AI answers?

Often, yes. Cloudflare Crawler (Browser Run) is a utility crawler, so pages it cannot fetch can drop out of the answers or results it supports.

Related: how AI engines choose their sources

Test yourself: is User-agent: cloudflarebrowserrenderingcrawler the same as User-agent: CloudflareBrowserRenderingCrawler?

Yes. RFC 9309 makes user-agent matching case-insensitive. Paths are a different story: Disallow: /Blog/ does not block /blog/.

Should you allow Cloudflare Crawler (Browser Run)? Decide by situation

Recommended setting for Cloudflare Crawler (Browser Run) by type of site
If you are...Recommended setting
You publish content and want AI answers to cite itLow stakes either way. It does not decide whether AI answers cite you.
You license content and want to stop AI trainingBlocking it does not stop training, because Cloudflare Crawler (Browser Run) is a utility crawler. Block the operator's training crawler instead.
You run an online shopAllow it unless your logs show it is costly.
Your server is under load from botsRate-limit before blocking. It is rated safe in our database.

Check Cloudflare Crawler (Browser Run) on your own site

  1. Open /robots.txt on your domain and search for CloudflareBrowserRenderingCrawler. If it is not named, it follows User-agent: *.
  2. List the Disallow lines in the group Cloudflare Crawler (Browser Run) follows and test your key URLs against them; the longest match wins, and Allow wins a tie.
  3. Look beyond the file. A firewall or bot manager can refuse Cloudflare Crawler (Browser Run) even when robots.txt allows it, and that never shows in the file.
  4. Run our free AI crawler check to see how Cloudflare Crawler (Browser Run) and every other crawler we track are treated in one pass, including firewall refusals.

Common mistakes with Cloudflare Crawler (Browser Run)

The errors we see most often with Cloudflare Crawler (Browser Run) in the files and firewalls we test:

  1. Treating Cloudflare Crawler (Browser Run) as an AI or search crawler. Blocking it has little effect on visibility; decide based on load and what it does with your data.
  2. Relying on robots.txt alone when Cloudflare Crawler (Browser Run) is rated caution or aggressive. Back the rule with a server-side block.
  3. Blocking Cloudflare Crawler (Browser Run) by IP alone. Ranges change; match the token and verify with logs.

All three hide inside a file that looks correct, so check Cloudflare Crawler (Browser Run) from outside after every change.

Spotting Cloudflare Crawler (Browser Run) in your logs

robots.txt says what Cloudflare Crawler (Browser Run) may do; your access logs show what it actually did.

Count requests

On a server with standard Nginx or Apache logs, this counts matching requests per day (adjust the log path for your host):

grep -iE "CloudflareBrowserRenderingCrawler" /var/log/nginx/access.log \
  | awk '{print $4}' | cut -d: -f1 | sort | uniq -c

And this shows which paths it requested most, which is the quickest way to see whether your Disallow lines are being respected:

grep -iE "CloudflareBrowserRenderingCrawler" /var/log/nginx/access.log \
  | awk '{print $7}' | sort | uniq -c | sort -rn | head -20

Check the requests are genuine

Anyone can send the Cloudflare Crawler (Browser Run) user-agent, so confirm the source before acting on a match:

  • CloudflareBrowserRenderingCrawler: we hold no published IP list, so use reverse DNS where the operator documents a hostname and treat an unverifiable Cloudflare Crawler (Browser Run) request with caution.

Frequently Asked Questions

What is the official user-agent string for Cloudflare Crawler (Browser Run)?
The official user-agent string for Cloudflare Crawler (Browser Run) is: CloudflareBrowserRenderingCrawler. Use this exact string in robots.txt, Nginx, Apache, or Cloudflare firewall rules to target this bot. Matching in robots.txt is case-insensitive. Cloudflare says Browser Run requests carry signature headers that point at Cloudflare's bot verification keys. Use the bot detection IDs Cloudflare publishes for WAF rules.
Is Cloudflare Crawler (Browser Run) safe?
Yes. Cloudflare Crawler (Browser Run) is a documented bot: Cloudflare publishes a page that names it and explains what it does.
Will blocking Cloudflare Crawler (Browser Run) hurt my SEO?
Blocking it stops Cloudflare customers crawling your site through Browser Run /crawl. It has no effect on Google or Bing.
How do I block Cloudflare Crawler (Browser Run) in robots.txt?
Add the following lines to your /robots.txt file:
User-agent: CloudflareBrowserRenderingCrawler
Disallow: /

This instructs Cloudflare Crawler (Browser Run) not to crawl any path on your site. To block only specific sections, replace / with the path (e.g., Disallow: /blog/).
Does Cloudflare Crawler (Browser Run) respect robots.txt?
Yes. Cloudflare documents robots.txt control for it, including Crawl-delay. Other Browser Run endpoints use a different user agent, so this token only covers /crawl.
How do I verify if Cloudflare Crawler (Browser Run) is crawling my site?
Search your web server access logs for the string CloudflareBrowserRenderingCrawler (case-insensitive: grep -i "CloudflareBrowserRenderingCrawler" /var/log/nginx/access.log). Filter by user-agent in your log analytics tool (GoAccess, AWStats, etc.).

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