GTmetrix
GTmetrix •
Since 2009
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Official Docs
What is GTmetrix?
GTmetrix is a popular website performance testing tool that analyzes page load speed and provides optimization recommendations. The bot uses Google's Lighthouse and custom metrics to evaluate performance, structure, and user experience. GTmetrix provides detailed waterfall charts, video capture of page loads, and historical performance tracking. The service is widely used by developers and SEO professionals to identify performance bottlenecks and monitor improvements over time. With both free and paid options, GTmetrix has become a standard tool for web performance optimization.
User Agent String
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 GTmetrix
How to Control GTmetrix
Block Completely
To prevent GTmetrix from accessing your entire website, add this to your robots.txt file:
# Block GTmetrix
User-agent: GTmetrix
Disallow: /
Block Specific Directories
To restrict access to certain parts of your site while allowing others:
User-agent: GTmetrix
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: GTmetrix
Crawl-delay: 10
How to Verify GTmetrix
Verification Method:
Tests originate from GTmetrix servers
Tests originate from GTmetrix servers
Learn more in the official documentation.
Detection Patterns
Multiple ways to detect GTmetrix in your application:
Basic Pattern
/GTmetrix/iStrict Pattern
/^Mozilla/5\.0 \(X11; Linux x86_64\) AppleWebKit/537\.36 \(KHTML, like Gecko\) Chrome/120\.0\.0\.0 Safari/537\.36 GTmetrix$/Flexible Pattern
/GTmetrix[\s\/]?[\d\.]*?/iVendor Match
/.*GTmetrix.*GTmetrix/iImplementation Examples
// PHP Detection for GTmetrix
function detect_gtmetrix() {
$user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
$pattern = '/GTmetrix/i';
if (preg_match($pattern, $user_agent)) {
// Log the detection
error_log('GTmetrix 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($_SERVER['REQUEST_URI']) . '.html');
exit;
}
return true;
}
return false;
}
# Python/Flask Detection for GTmetrix
import re
from flask import request, make_responsedef detect_gtmetrix():
user_agent = request.headers.get('User-Agent', '')
pattern = r'GTmetrix'
if re.search(pattern, user_agent, re.IGNORECASE):
# Create response with caching
response = make_response()
response.headers['Cache-Control'] = 'public, max-age=3600'
response.headers['X-Robots-Tag'] = 'noarchive'
return True
return False# Django Middleware
class GTmetrixMiddleware:
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
if self.detect_bot(request):
# Handle bot traffic
pass
return self.get_response(request)
// JavaScript/Node.js Detection for GTmetrix
const express = require('express');
const app = express();// Middleware to detect GTmetrix
function detectGTmetrix(req, res, next) {
const userAgent = req.headers['user-agent'] || '';
const pattern = /GTmetrix/i;
if (pattern.test(userAgent)) {
// Log bot detection
console.log('GTmetrix detected from IP:', req.ip);
// Set cache headers
res.set({
'Cache-Control': 'public, max-age=3600',
'X-Robots-Tag': 'noarchive'
});
// Mark request as bot
req.isBot = true;
req.botName = 'GTmetrix';
}
next();
}app.use(detectGTmetrix);
# Apache .htaccess rules for GTmetrix# Block completely
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} GTmetrix [NC]
RewriteRule .* - [F,L]# Or redirect to a static version
RewriteCond %{HTTP_USER_AGENT} GTmetrix [NC]
RewriteCond %{REQUEST_URI} !^/static/
RewriteRule ^(.*)$ /static/$1 [L]# Or set environment variable for PHP
SetEnvIfNoCase User-Agent "GTmetrix" is_bot=1# Add cache headers for this bot
<If "%{HTTP_USER_AGENT} =~ /GTmetrix/i">
Header set Cache-Control "public, max-age=3600"
Header set X-Robots-Tag "noarchive"
</If>
# Nginx configuration for GTmetrix# Map user agent to variable
map $http_user_agent $is_gtmetrix {
default 0;
~*GTmetrix 1;
}server {
# Block the bot completely
if ($is_gtmetrix) {
return 403;
}
# Or serve cached content
location / {
if ($is_gtmetrix) {
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_gtmetrix) {
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: GTmetrix
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: GTmetrix
Crawl-delay: 10
Disallow: /wp-admin/
Disallow: /drafts/
Disallow: /preview/
Disallow: /*?replytocom=
Allow: /
SaaS/Application Configuration
User-agent: GTmetrix
Disallow: /app/
Disallow: /api/
Disallow: /dashboard/
Disallow: /settings/
Allow: /
Allow: /pricing/
Allow: /features/
Allow: /docs/
Quick Reference
User Agent Match
GTmetrixRobots.txt Name
GTmetrixCategory
monitoring, seoRespects robots.txt
Yes
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