YandexImageResizer
Yandex •
Web Crawler
What is YandexImageResizer?
Yandex lists YandexImageResizer as a mobile-devices robot and provides this full header. The published table says it takes general robots.txt rules into account. The documentation does not explain the exact transformation pipeline, so this entry does not claim which image sizes or products it serves. It is separate from YandexImages, which indexes images for Yandex Images search.
User Agent String
Mozilla/5.0 (compatible; YandexImageResizer/2.0; +http://yandex.com/bots)
How to Control YandexImageResizer
Block Completely
To prevent YandexImageResizer from accessing your entire website, add this to your robots.txt file:
# Block YandexImageResizer
User-agent: YandexImageResizer
Disallow: /
Block Specific Directories
To restrict access to certain parts of your site while allowing others:
User-agent: YandexImageResizer
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: YandexImageResizer
Crawl-delay: 10
How to Verify YandexImageResizer
Verification Method:
Confirm the source using Yandex-domain reverse DNS and a matching forward lookup.
Confirm the source using Yandex-domain reverse DNS and a matching forward lookup.
Learn more in the official documentation.
Detection Patterns
Multiple ways to detect YandexImageResizer in your application:
Basic Pattern
/YandexImageResizer/i
Strict Pattern
/^Mozilla\/5\.0 \(compatible; YandexImageResizer\/2\.0; \+http\:\/\/yandex\.com\/bots\)$/
Flexible Pattern
/YandexImageResizer[\s\/]?[\d\.]*?/i
Vendor Match
/.*Yandex.*YandexImageResizer/i
Implementation Examples
// PHP Detection for YandexImageResizer
function detect_yandeximageresizer() {
$user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
$pattern = '/YandexImageResizer/i';
if (preg_match($pattern, $user_agent)) {
// Log the detection
error_log('YandexImageResizer 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($_SERVER['REQUEST_URI']) . '.html');
exit;
}
return true;
}
return false;
}
# Python/Flask Detection for YandexImageResizer
import re
from flask import request, make_response
def detect_yandeximageresizer():
user_agent = request.headers.get('User-Agent', '')
pattern = r'YandexImageResizer'
if re.search(pattern, user_agent, re.IGNORECASE):
# Create response with caching
response = make_response()
response.headers['Cache-Control'] = 'public, max-age=3600'
response.headers['X-Robots-Tag'] = 'noarchive'
return True
return False
# Django Middleware
class yandeximageresizerMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
if self.detect_bot(request):
# Handle bot traffic
pass
return self.get_response(request)
// JavaScript/Node.js Detection for YandexImageResizer
const express = require('express');
const app = express();
// Middleware to detect YandexImageResizer
function detect_yandeximageresizer(req, res, next) {
const userAgent = req.headers['user-agent'] || '';
const pattern = /YandexImageResizer/i;
if (pattern.test(userAgent)) {
// Log bot detection
console.log('YandexImageResizer detected from IP:', req.ip);
// Set cache headers
res.set({
'Cache-Control': 'public, max-age=3600',
'X-Robots-Tag': 'noarchive'
});
// Mark request as bot
req.isBot = true;
req.botName = 'YandexImageResizer';
}
next();
}
app.use(detect_yandeximageresizer);
# Apache .htaccess rules for YandexImageResizer
# Block completely
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} YandexImageResizer [NC]
RewriteRule .* - [F,L]
# Or redirect to a static version
RewriteCond %{HTTP_USER_AGENT} YandexImageResizer [NC]
RewriteCond %{REQUEST_URI} !^/static/
RewriteRule ^(.*)$ /static/$1 [L]
# Or set environment variable for PHP
SetEnvIfNoCase User-Agent "YandexImageResizer" is_bot=1
# Add cache headers for this bot
<If "%{HTTP_USER_AGENT} =~ /YandexImageResizer/i">
Header set Cache-Control "public, max-age=3600"
Header set X-Robots-Tag "noarchive"
</If>
# Nginx configuration for YandexImageResizer
# Map user agent to variable
map $http_user_agent $is_yandeximageresizer {
default 0;
~*YandexImageResizer 1;
}
server {
# Block the bot completely
if ($is_yandeximageresizer) {
return 403;
}
# Or serve cached content
location / {
if ($is_yandeximageresizer) {
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_yandeximageresizer) {
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 | Allow | Essential for product visibility in search results |
| Blog/News | Allow | Increases content reach and discoverability |
| SaaS Application | Block | No benefit for application interfaces; preserve resources |
| Documentation | Allow | Improves documentation discoverability for developers |
| Corporate Site | Allow | Allow for public pages, block sensitive areas like intranets |
Advanced robots.txt Configurations
E-commerce Site Configuration
User-agent: YandexImageResizer
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: YandexImageResizer
Crawl-delay: 10
Disallow: /wp-admin/
Disallow: /drafts/
Disallow: /preview/
Disallow: /*?replytocom=
Allow: /
SaaS/Application Configuration
User-agent: YandexImageResizer
Disallow: /app/
Disallow: /api/
Disallow: /dashboard/
Disallow: /settings/
Allow: /
Allow: /pricing/
Allow: /features/
Allow: /docs/
Quick Reference
User Agent Match
YandexImageResizer
Robots.txt Name
YandexImageResizer
Category
search
Respects robots.txt
Yes
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