GTmetrix
PerformanceWebsite speed testing with waterfall analysis and Core Web Vitals
Overview
GTmetrix has been the go-to speed testing tool for web developers and SEO professionals since 2010, long before Core Web Vitals became a Google ranking factor. Built by Carbon60 in Vancouver, it combines Google PageSpeed and Yahoo YSlow metrics with detailed waterfall charts that show exactly where performance bottlenecks occur. Unlike Google's PageSpeed Insights, which focuses on optimization recommendations, GTmetrix excels at diagnosing the root causes of slow page loads.
The tool's strength lies in its comprehensive approach to performance analysis. Where PageSpeed Insights gives you a score and suggestions, GTmetrix shows you the actual loading sequence of every resource on your page. This makes it invaluable for developers who need to optimize third-party scripts, CDN configurations, or server response times. The waterfall charts clearly identify render-blocking resources, oversized images, and slow database queries that other tools might miss.
GTmetrix has evolved to include Core Web Vitals monitoring alongside its traditional metrics, though it still emphasizes the technical diagnostics that made it popular. The free tier provides substantial functionality for individual users, while paid plans add automated monitoring and team features that make it practical for agencies managing multiple client sites.
Key features
Waterfall Chart Analysis
Detailed request-by-request breakdown showing exactly which resources are slowing down your page load times.
Core Web Vitals Monitoring
Tracks Google's essential user experience metrics including LCP, FID, and CLS with historical data.
Multiple Test Locations
Test from 20+ global locations to understand performance variations across different geographic regions.
Performance Video Capture
Records actual page loading process to visualize render blocking and identify optimization opportunities.
Historical Performance Tracking
Monitors page speed changes over time with automated testing schedules and alerting.
PageSpeed and YSlow Scoring
Dual scoring system based on Google PageSpeed Insights and Yahoo YSlow methodologies.
Pricing
| Plan | Price | Includes |
|---|---|---|
| Free | Free | 10 tests/hour, basic monitoring, PDF reports |
| Basic | $10/month | Unlimited tests, 5 locations, hourly monitoring |
| Premium | $25/month | 20 locations, video capture, API access |
| Pro | $50/month | Custom locations, white-label reports, team collaboration |
FAQ
How accurate is GTmetrix compared to PageSpeed Insights?
GTmetrix tests from real browser environments while PageSpeed Insights uses lab data. GTmetrix typically shows more realistic loading times but PageSpeed Insights aligns better with Google's ranking factors.
Can GTmetrix test password-protected pages?
Yes, paid plans include HTTP authentication support for testing staging sites and member-only areas behind login screens.
What's the difference between GTmetrix and other speed testing tools?
GTmetrix focuses heavily on waterfall analysis and provides more detailed resource-level insights, while tools like PageSpeed Insights emphasize Core Web Vitals optimization recommendations.
Does GTmetrix affect my website's server performance?
GTmetrix tests generate minimal server load since they only request your pages like normal visitors, but frequent automated monitoring from multiple locations can add up.
How often should I run GTmetrix tests on my website?
For active sites, weekly automated tests catch performance regressions early. Run manual tests immediately after any major changes to themes, plugins, or content.
Review Sentiment
73 reviews across 2 sources
Bottom line
Hard to beat free. GTmetrix is a genuine asset for web developers thanks to detailed waterfall charts and filmstrip views, though limited test server locations reduce global coverage keeps it from replacing paid alternatives entirely.
People love
- +Detailed waterfall charts and filmstrip views for diagnosing page speed issues
- +Customizable test regions, devices, and browser settings for thorough analysis
- +Excellent free tier provides actionable Lighthouse-based performance reports
Common complaints
- –Limited test server locations reduce global coverage
- –Doesn't clearly explain how to fix the issues it identifies
- –Results can vary significantly between consecutive tests, causing confusion
Last updated Feb 2026