Slackbot
Slack •
Since 2014
Quick Actions
Official Docs
What is Slackbot?
Slackbot-LinkExpanding is Slack's crawler that automatically expands links shared in Slack workspaces, creating rich previews with titles, descriptions, and images. This functionality is crucial for workplace communication, helping teams quickly understand shared content without leaving Slack. The bot respects standard meta tags and can be customized through Slack's API for app integrations. For SaaS companies and B2B content creators, optimizing for Slackbot ensures their content is effectively presented in workplace conversations. The crawler also supports special Slack app unfurling for enhanced integrations.
User Agent String
Slackbot-LinkExpanding 1.0 (+https://api.slack.com/robots)
How to Control Slackbot
Block Completely
To prevent Slackbot from accessing your entire website, add this to your robots.txt file:
# Block Slackbot
User-agent: Slackbot
Disallow: /
Block Specific Directories
To restrict access to certain parts of your site while allowing others:
User-agent: Slackbot
Disallow: /admin/
Disallow: /private/
Disallow: /wp-admin/
Allow: /public/
Set Crawl Delay
To slow down the crawl rate (note: not all bots respect this directive):
User-agent: Slackbot
Crawl-delay: 10
How to Verify Slackbot
Verification Method:
Check Slack's published IP ranges
Check Slack's published IP ranges
Learn more in the official documentation.
Detection Patterns
Multiple ways to detect Slackbot in your application:
Basic Pattern
/Slackbot/i
Strict Pattern
/^Slackbot\-LinkExpanding 1\.0 \(\+https\://api\.slack\.com/robots\)$/
Flexible Pattern
/Slackbot[\s\/]?[\d\.]*?/i
Vendor Match
/.*Slack.*Slackbot/i
Implementation Examples
// PHP Detection for Slackbot
function detect_slackbot() {
$user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
$pattern = '/Slackbot/i';
if (preg_match($pattern, $user_agent)) {
// Log the detection
error_log('Slackbot detected from IP: ' . $_SERVER['REMOTE_ADDR']);
// Set cache headers
header('Cache-Control: public, max-age=3600');
header('X-Robots-Tag: noarchive');
// Optional: Serve cached version
if (file_exists('cache/' . md5($_SERVER['REQUEST_URI']) . '.html')) {
readfile('cache/' . md5($_SERVER['REQUEST_URI']) . '.html');
exit;
}
return true;
}
return false;
}
# Python/Flask Detection for Slackbot
import re
from flask import request, make_response
def detect_slackbot():
user_agent = request.headers.get('User-Agent', '')
pattern = r'Slackbot'
if re.search(pattern, user_agent, re.IGNORECASE):
# Create response with caching
response = make_response()
response.headers['Cache-Control'] = 'public, max-age=3600'
response.headers['X-Robots-Tag'] = 'noarchive'
return True
return False
# Django Middleware
class SlackbotMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
if self.detect_bot(request):
# Handle bot traffic
pass
return self.get_response(request)
// JavaScript/Node.js Detection for Slackbot
const express = require('express');
const app = express();
// Middleware to detect Slackbot
function detectSlackbot(req, res, next) {
const userAgent = req.headers['user-agent'] || '';
const pattern = /Slackbot/i;
if (pattern.test(userAgent)) {
// Log bot detection
console.log('Slackbot detected from IP:', req.ip);
// Set cache headers
res.set({
'Cache-Control': 'public, max-age=3600',
'X-Robots-Tag': 'noarchive'
});
// Mark request as bot
req.isBot = true;
req.botName = 'Slackbot';
}
next();
}
app.use(detectSlackbot);
# Apache .htaccess rules for Slackbot
# Block completely
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} Slackbot [NC]
RewriteRule .* - [F,L]
# Or redirect to a static version
RewriteCond %{HTTP_USER_AGENT} Slackbot [NC]
RewriteCond %{REQUEST_URI} !^/static/
RewriteRule ^(.*)$ /static/$1 [L]
# Or set environment variable for PHP
SetEnvIfNoCase User-Agent "Slackbot" is_bot=1
# Add cache headers for this bot
<If "%{HTTP_USER_AGENT} =~ /Slackbot/i">
Header set Cache-Control "public, max-age=3600"
Header set X-Robots-Tag "noarchive"
</If>
# Nginx configuration for Slackbot
# Map user agent to variable
map $http_user_agent $is_slackbot {
default 0;
~*Slackbot 1;
}
server {
# Block the bot completely
if ($is_slackbot) {
return 403;
}
# Or serve cached content
location / {
if ($is_slackbot) {
root /var/www/cached;
try_files $uri $uri.html $uri/index.html @backend;
}
try_files $uri @backend;
}
# Add headers for bot requests
location @backend {
if ($is_slackbot) {
add_header Cache-Control "public, max-age=3600";
add_header X-Robots-Tag "noarchive";
}
proxy_pass http://backend;
}
}
Should You Block This Bot?
Recommendations based on your website type:
| Site Type | Recommendation | Reasoning |
|---|---|---|
| E-commerce | Optional | Evaluate based on bandwidth usage vs. benefits |
| Blog/News | Allow | Increases content reach and discoverability |
| SaaS Application | Block | No benefit for application interfaces; preserve resources |
| Documentation | Selective | Allow for public docs, block for internal docs |
| Corporate Site | Limit | Allow for public pages, block sensitive areas like intranets |
Advanced robots.txt Configurations
E-commerce Site Configuration
User-agent: Slackbot
Crawl-delay: 5
Disallow: /cart/
Disallow: /checkout/
Disallow: /my-account/
Disallow: /api/
Disallow: /*?sort=
Disallow: /*?filter=
Disallow: /*&page=
Allow: /products/
Allow: /categories/
Sitemap: https://example.com/sitemap.xml
Publishing/Blog Configuration
User-agent: Slackbot
Crawl-delay: 10
Disallow: /wp-admin/
Disallow: /drafts/
Disallow: /preview/
Disallow: /*?replytocom=
Allow: /
SaaS/Application Configuration
User-agent: Slackbot
Disallow: /app/
Disallow: /api/
Disallow: /dashboard/
Disallow: /settings/
Allow: /
Allow: /pricing/
Allow: /features/
Allow: /docs/
Quick Reference
User Agent Match
Slackbot
Robots.txt Name
Slackbot
Category
social
Respects robots.txt
Yes
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