What is SemrushBot-OCOB? Semrush's SEO crawler
SemrushBot-OCOB is the Semrush bot behind Content Toolkit.
72 of the 1662 major websites we measure block SemrushBot-OCOB in robots.txt (4%). 42 of those sites name it directly in their robots.txt; the rest are covered by a wildcard rule.
Key facts
| Fact | Detail |
|---|---|
| Operator | Semrush |
| Used for | Semrush Content Toolkit |
| Type | SEO tool. Collects web data for an SEO tool. Listed here because people look it up beside AI crawlers. It isn't counted in the AI crawler figures. |
| robots.txt token | SemrushBot-OCOB |
| Operator's documentation | Read it here |
What blocking SemrushBot-OCOB does
Semrush says each of its tool bots can be blocked on its own with a robots.txt group that names it, separately from SemrushBot.
How to allow or block SemrushBot-OCOB
Add one of these groups to the robots.txt file at the root of your domain. It is a stated preference that well-behaved crawlers read, not an enforcement mechanism.
User-agent: SemrushBot-OCOB Disallow: /
User-agent: SemrushBot-OCOB Allow: /
SemrushBot-OCOB user agent string
Semrush's page doesn't list a full string, so look for SemrushBot-OCOB in the user agent field of your logs.
How to verify a request is really SemrushBot-OCOB
Anyone can put a crawler's name in a user agent string, so the name alone proves nothing. We did not find a published IP list or reverse DNS rule from Semrush.
How to whitelist SemrushBot-OCOB in a firewall or CDN
robots.txt only states a preference. A firewall, CDN or bot protection service can still refuse the request, and the crawler then gets an error even though robots.txt allows it.
- Check that no group in your robots.txt blocks it, using the rule above.
- Add an allow rule in your firewall or CDN that matches the name in the user agent. Keep the rule narrow, because anyone can copy a name.
- Check your server logs for a 200 response from SemrushBot-OCOB afterwards.
On Cloudflare, also check AI Crawler and Agent access policies, which can block search, agent and training traffic across a site.
Why SemrushBot-OCOB gets a 403 or 405 error
A 403 means the server refused the request, which usually points to a firewall or bot rule. A 405 means the server refused the request's method, so check any rule that only permits certain methods. A crawler that obeys robots.txt won't request a page it is told to avoid, so an error in your logs points to your server's configuration. To stop it deliberately at the server, this nginx rule returns a 403:
if ($http_user_agent ~* "SemrushBot-OCOB") {
return 403;
}Who blocks SemrushBot-OCOB, by sector
| Sector | Sites measured | Blocking | Share |
|---|---|---|---|
| News publishers | 182 | 25 | 14% |
| Social and media platforms | 115 | 12 | 10% |
| Technology media | 126 | 12 | 10% |
| Health publishers | 88 | 4 | 5% |
| Reference and research | 114 | 4 | 4% |
| AI companies | 128 | 4 | 3% |
| Finance and business media | 94 | 3 | 3% |
| Government and institutions | 98 | 2 | 2% |
| Developer references | 159 | 1 | 1% |
| E-commerce and retail | 92 | 1 | 1% |
| Hosting and infrastructure | 98 | 1 | 1% |
| SaaS platforms | 196 | 2 | 1% |
| Travel | 86 | 1 | 1% |
| SEO and marketing tools | 86 | 0 | 0% |
Sites blocking SemrushBot-OCOB
academia.edu, aftenposten.no, afterpay.com, aftonbladet.se, azcentral.com, babycenter.com, barrons.com, bild.de, cnn.com, congress.gov, consilium.europa.eu, devclass.com, disneyplus.com, distill.pub, eluniversal.com.mx, eurogamer.net, everydayhealth.com, extremetech.com, facebook.com, flickr.com, fortinet.com, gamesindustry.biz, getyourguide.com, golem.de, hackernoon.com, ign.com, imdb.com, instacart.com, instagram.com, issuu.com, jamanetwork.com, lemonde.fr, lesechos.fr, lifehacker.com, linguee.com, lobste.rs, magento.com, marketwatch.com, mashable.com, meta.ai, netflix.com, news.com.au, nrc.nl, poe.com, politico.com, postman.com, publico.pt, reddit.com, reuters.com, rockpapershotgun.com, sap.com, sciencedirect.com, semafor.com, snapchat.com, svd.se, t3n.de, theregister.com, theresanaiforthat.com, thestar.com, thesun.co.uk, and 12 more in the full dataset.
Sites that allow SemrushBot-OCOB by name
clickfunnels.com, foreignpolicy.com, pcmag.com, pinterest.com, slate.com, unsplash.com.
Other Semrush crawlers
SemrushBot (SEO index), SiteAuditBot (SEO site audit), SemrushBot-BA (SEO backlink audit), SemrushBot-SI (SEO page checks), SemrushBot-SWA (SEO writing checks), SplitSignalBot (SEO A/B tests), SemrushBot-FT (plagiarism checks), RyteBot (SEO site audit), SemrushBot-ESI (enterprise site data).
See all 36 AI crawlers, the rule change log or the full study. Being reachable is only the first step: how AI search engines choose what to cite covers the rest.
Cite this data
You are welcome to quote or republish these figures. Please credit IndexHalo with a link to this page (CC BY 4.0). All our datasets are on the data page.
IndexHalo. "SemrushBot-OCOB block rate across major websites." Measured 12 November 2026. https://www.indexhalo.com/ai-crawlers/semrushbot-ocob/
<a href="https://www.indexhalo.com/ai-crawlers/semrushbot-ocob/">SemrushBot-OCOB block rate across major websites, IndexHalo</a>