GTmetrix is a web-based service for testing and monitoring website performance that generates Lighthouse-based metrics, grades, and structured audits, enriched with real-user Chrome UX Report (CrUX) data where available. It offers global test locations, mobile emulation, connection throttling, video capture, and detailed waterfalls to diagnose load sequencing, slow or broken requests, and third-party impacts. Monitoring schedules with alerting and historical graphs enable ongoing performance tracking; GTmetrix PRO adds hourly monitoring, more locations, extended CrUX history, and advanced analysis controls such as custom DNS, user agent, and viewport settings.

Key Features

Lighthouse-based analysis and audits Actionable metrics and structure insights.

• GTmetrix Grade with Performance/Structure scores and Web Vitals from Lighthouse.
• Audit recommendations to guide optimization priorities.

CrUX real-user data integration Context from field data.

• Incorporates Chrome UX Report metrics for real-user performance where available.
• GTmetrix PRO extends CrUX history to 6 months for trend analysis. Global and mobile testing Test like your users.
• Seven free global test locations, with 15 additional premium locations on PRO.
• Mobile testing available on PRO to emulate device conditions.

Detailed waterfall and request inspection Request-by-request visibility.

• Waterfall charts showing order, timing, headers, CDN cache status, IPs, and more.
• Filter/sort by type, status, size, or domain to isolate bottlenecks.

Monitoring, history, and alerts Track changes over time.

• Schedule daily/weekly/monthly tests with history graphs for Web Vitals, grades, size, and requests.
• Email alerts on conditions you define to catch regressions.
• Hourly monitoring on PRO for finer-grain tracking.

Scenario and environment controls Reproduce real conditions.

• Connection throttling for different speeds and custom connections on PRO.
• Block ads in tests to assess third‑party impact; video playback to visualize load and milestones.
• Custom DNS, user agent, and screen resolution on PRO for staging/dev and device scenarios.

Benefits

Faster, more reliable pages Measurable performance gains.

• Pinpoints high-impact issues using Lighthouse audits and Web Vitals.
• Validates improvements with monitoring trends and alerts to prevent regressions.

Realistic user-centric insights Decisions based on field and lab data.

• Combines synthetic tests with CrUX field performance for context across audiences.
• Tests from user-relevant regions and mobile profiles to match real conditions.

Efficient troubleshooting and collaboration Quicker root cause analysis.

• Waterfalls, headers, and video reveal sequencing, third-party delays, and failures.
• Organization features like unlimited tagging and filter tabs on PRO streamline team workflows.