What is Slackbot? Slack's link preview crawler
Slackbot's link expander fetches a small part of a page when someone posts its link in Slack, to build the preview from the page's meta tags.
26 of the 1664 major websites we measure block Slackbot in robots.txt (2%). 16 of those sites name it directly in their robots.txt; the rest are covered by a wildcard rule.
Key facts
| Fact | Detail |
|---|---|
| Operator | Slack |
| Used for | Link previews in Slack |
| Type | Link preview. Fetches a page to show a preview when someone shares its link. It isn't counted in the AI crawler figures. |
| robots.txt token | Slackbot |
| Operator's documentation | Read it here |
What blocking Slackbot does
Slack says it does not currently honour robots.txt files, because the link expander acts for a user and does not follow links, and that a site owner who wants to block Slack previews must contact Slack.
How to allow or block Slackbot
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: Slackbot Disallow: /
User-agent: Slackbot Allow: /
Slackbot user agent string
The string Slack documents. Version numbers can change, so match on the name.
Slackbot-LinkExpanding 1.0 (+https://api.slack.com/robots)
How to verify a request is really Slackbot
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 Slack.
How to whitelist Slackbot 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 Slackbot afterwards.
On Cloudflare, also check AI Crawler and Agent access policies, which can block search, agent and training traffic across a site.
Why Slackbot 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 ~* "Slackbot") {
return 403;
}Who blocks Slackbot, by sector
| Sector | Sites measured | Blocking | Share |
|---|---|---|---|
| Social and media platforms | 115 | 9 | 8% |
| Finance and business media | 94 | 3 | 3% |
| Reference and research | 114 | 3 | 3% |
| AI companies | 128 | 3 | 2% |
| News publishers | 182 | 3 | 2% |
| E-commerce and retail | 92 | 1 | 1% |
| Government and institutions | 98 | 1 | 1% |
| Hosting and infrastructure | 98 | 1 | 1% |
| SaaS platforms | 196 | 2 | 1% |
| Developer references | 160 | 0 | 0% |
| Health publishers | 89 | 0 | 0% |
| SEO and marketing tools | 86 | 0 | 0% |
| Technology media | 126 | 0 | 0% |
| Travel | 86 | 0 | 0% |
Sites blocking Slackbot
afterpay.com, barrons.com, consilium.europa.eu, disneyplus.com, distill.pub, facebook.com, fortinet.com, imdb.com, instacart.com, instagram.com, linguee.com, lobste.rs, magento.com, marketwatch.com, meta.ai, netflix.com, poe.com, reddit.com, reuters.com, sap.com, sciencedirect.com, threads.net, todayonline.com, wordreference.com, wsj.com, x.com.
Sites that allow Slackbot by name
academia.edu, coinbase.com, devclass.com, eluniversal.com.mx, flickr.com, hackernoon.com, lovable.dev, news.com.au, pinterest.com, salon.com, scale.com, theregister.com, thesun.co.uk, thetimes.co.uk, zeit.de, zoom.us.
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. "Slackbot block rate across major websites." Measured 12 November 2026. https://www.indexhalo.com/ai-crawlers/slackbot/
<a href="https://www.indexhalo.com/ai-crawlers/slackbot/">Slackbot block rate across major websites, IndexHalo</a>