Google-CWS
Google •
Web Crawler
What is Google-CWS?
Google lists Google-CWS as the Chrome Web Store fetcher. It requests URLs that extension and theme developers provide in their Chrome Web Store metadata, rather than crawling the web for a search index. Google groups it with user-triggered fetchers, which generally ignore robots.txt because the request was initiated through a product workflow.
User Agent String
Mozilla/5.0 (compatible; Google-CWS)
How to Control Google-CWS
Block Completely
To prevent Google-CWS from accessing your entire website, add this to your robots.txt file:
# Block Google-CWS
User-agent: Google-CWS
Disallow: /
Block Specific Directories
To restrict access to certain parts of your site while allowing others:
User-agent: Google-CWS
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: Google-CWS
Crawl-delay: 10
How to Verify Google-CWS
Verification Method:
Verify source addresses against Google's user-triggered fetcher IP ranges; the user-agent string alone is not proof.
Verify source addresses against Google's user-triggered fetcher IP ranges; the user-agent string alone is not proof.
Learn more in the official documentation.
Detection Patterns
Multiple ways to detect Google-CWS in your application:
Basic Pattern
/Google\-CWS/i
Strict Pattern
/^Mozilla\/5\.0 \(compatible; Google\-CWS\)$/
Flexible Pattern
/Google\-CWS[\s\/]?[\d\.]*?/i
Vendor Match
/.*Google.*Google\-CWS/i
Implementation Examples
// PHP Detection for Google-CWS
function detect_google_cws() {
$user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
$pattern = '/Google\-CWS/i';
if (preg_match($pattern, $user_agent)) {
// Log the detection
error_log('Google-CWS 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($_SERVER['REQUEST_URI']) . '.html');
exit;
}
return true;
}
return false;
}
# Python/Flask Detection for Google-CWS
import re
from flask import request, make_response
def detect_google_cws():
user_agent = request.headers.get('User-Agent', '')
pattern = r'Google\-CWS'
if re.search(pattern, user_agent, re.IGNORECASE):
# Create response with caching
response = make_response()
response.headers['Cache-Control'] = 'public, max-age=3600'
response.headers['X-Robots-Tag'] = 'noarchive'
return True
return False
# Django Middleware
class google_cwsMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
if self.detect_bot(request):
# Handle bot traffic
pass
return self.get_response(request)
// JavaScript/Node.js Detection for Google-CWS
const express = require('express');
const app = express();
// Middleware to detect Google-CWS
function detect_google_cws(req, res, next) {
const userAgent = req.headers['user-agent'] || '';
const pattern = /Google\-CWS/i;
if (pattern.test(userAgent)) {
// Log bot detection
console.log('Google-CWS detected from IP:', req.ip);
// Set cache headers
res.set({
'Cache-Control': 'public, max-age=3600',
'X-Robots-Tag': 'noarchive'
});
// Mark request as bot
req.isBot = true;
req.botName = 'Google-CWS';
}
next();
}
app.use(detect_google_cws);
# Apache .htaccess rules for Google-CWS
# Block completely
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} Google\-CWS [NC]
RewriteRule .* - [F,L]
# Or redirect to a static version
RewriteCond %{HTTP_USER_AGENT} Google\-CWS [NC]
RewriteCond %{REQUEST_URI} !^/static/
RewriteRule ^(.*)$ /static/$1 [L]
# Or set environment variable for PHP
SetEnvIfNoCase User-Agent "Google\-CWS" is_bot=1
# Add cache headers for this bot
<If "%{HTTP_USER_AGENT} =~ /Google\-CWS/i">
Header set Cache-Control "public, max-age=3600"
Header set X-Robots-Tag "noarchive"
</If>
# Nginx configuration for Google-CWS
# Map user agent to variable
map $http_user_agent $is_google_cws {
default 0;
~*Google\-CWS 1;
}
server {
# Block the bot completely
if ($is_google_cws) {
return 403;
}
# Or serve cached content
location / {
if ($is_google_cws) {
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_google_cws) {
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: Google-CWS
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: Google-CWS
Crawl-delay: 10
Disallow: /wp-admin/
Disallow: /drafts/
Disallow: /preview/
Disallow: /*?replytocom=
Allow: /
SaaS/Application Configuration
User-agent: Google-CWS
Disallow: /app/
Disallow: /api/
Disallow: /dashboard/
Disallow: /settings/
Allow: /
Allow: /pricing/
Allow: /features/
Allow: /docs/
Quick Reference
User Agent Match
Google-CWS
Robots.txt Name
Google-CWS
Category
other
Respects robots.txt
May not respect
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