Slack-ImgProxy user agent
Operated by Slack
Slack-ImgProxy is the fetcher Slack uses to load and cache images shown in Slack messages.
The Slack-ImgProxy bot at a glance
- Slack-ImgProxy is operated by Slack and reads page titles, descriptions and images to build link previews.
- The robots.txt token for Slack-ImgProxy is Slack-ImgProxy.
- Blocking a social preview bot has no effect on search rankings.
- Slack-ImgProxy robots.txt support: Yes.
- Recommendation for Generative Engine Optimization (GEO): Allow.
What is Slack-ImgProxy?
Slack-ImgProxy downloads images from shared links and previews so Slack can display them through its own proxy.
Blocking it leaves image previews in Slack empty.
Should you block Slack-ImgProxy?
Allow Slack-ImgProxy unless it causes a measurable load problem.
| Effect on search rankings | Blocking a social preview bot has no effect on search rankings. |
|---|---|
| Effect on AI visibility | No direct effect on AI answers, but shared links lose their title, image and description, which usually lowers clicks from social and chat apps. |
| Follows robots.txt | Yes |
| Recommendation | Allow |
How to block or allow Slack-ImgProxy
Put the robots.txt rule in the file at the root of every domain and subdomain, for example https://example.com/robots.txt. The token Slack-ImgProxy is matched case-insensitively.
robots.txt: block
# Block Slack-ImgProxy
User-agent: Slack-ImgProxy
Disallow: /robots.txt: allow
# Allow Slack-ImgProxy
User-agent: Slack-ImgProxy
Allow: /robots.txt: partial
# Keep Slack-ImgProxy out of private areas only
User-agent: Slack-ImgProxy
Disallow: /wp-admin/
Disallow: /cart/
Disallow: /checkout/
Disallow: /my-account/
Allow: /Nginx
# Nginx: return 403 to Slack-ImgProxy
if ($http_user_agent ~* "(Slack\-ImgProxy)") {
return 403;
}Apache
# Apache .htaccess: return 403 to Slack-ImgProxy
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} (Slack\-ImgProxy) [NC]
RewriteRule .* - [F,L]Cloudflare WAF
# Cloudflare > Security > WAF > Custom rule, action: Block
(http.user_agent contains "Slack-ImgProxy")How to verify real Slack-ImgProxy traffic
Slack publishes no IP list or reverse DNS pattern for Slack-ImgProxy, so the user agent cannot be verified. Anyone can send the same string. Rate-limit unusual volume instead of trusting the name.
How to find Slack-ImgProxy in your server logs
Search the web server access log for the token. The command below counts Slack-ImgProxy requests per URL on Nginx or Apache.
grep -i "Slack-ImgProxy" access.log | awk '{print $7}' | sort | uniq -c | sort -rn | head -20For a full report per AI bot, upload the log to the AI Log File Analyzer, a free tool by Justin Hà.
Slack-ImgProxy user agent string
The full user agent Slack publishes for Slack-ImgProxy. Version numbers such as Chrome/W.X.Y.Z change over time, so match the token, not the whole string.
Slack-ImgProxy (+https://api.slack.com/robots)Slack-ImgProxy FAQ
Slack-ImgProxy identifies itself with the robots.txt token "Slack-ImgProxy". A typical request header reads: Slack-ImgProxy (+https://api.slack.com/robots)
Yes. Slack states that Slack-ImgProxy follows robots.txt rules written for the "Slack-ImgProxy" token.
Blocking a social preview bot has no effect on search rankings. No direct effect on AI answers, but shared links lose their title, image and description, which usually lowers clicks from social and chat apps.
Add two lines to the robots.txt file at the root of each domain and subdomain: "User-agent: Slack-ImgProxy" followed by "Disallow: /". The token is case-insensitive. Changes can take up to 24 hours to be picked up.
Not reliably. Slack publishes no IP list or reverse DNS pattern for Slack-ImgProxy, so anyone can send the same user agent. Rate-limit unusual volume instead of trusting the name.
Search your server access log for "Slack-ImgProxy", for example with: grep -i "Slack-ImgProxy" access.log. The AI Log File Analyzer by Justin Hà counts visits per AI bot from an uploaded log file.
Sources: Slack crawler documentation. Last reviewed by Justin Hà.
See which of these bots actually reach your website
The AI Log File Analyzer by Justin Hà counts visits from GPTBot, ClaudeBot, PerplexityBot and other AI crawlers in your server log, for free. The GEO Technical Package sets up robots.txt, llms.txt and crawler access for AI search.
