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About PageDiag

PageDiag is a free, open performance scanner built for ecommerce sites.

Enter any URL and get a detailed report covering Core Web Vitals, SEO best practices, and accessibility compliance — for both desktop and mobile. No account needed, no paywall.

How it works

PageDiag uses a headless Chromium browser to load your page under simulated real-world conditions (throttled CPU and network, matching Google Lighthouse methodology). It measures everything from First Contentful Paint to layout shifts, then generates actionable recommendations to help you improve.

Scoring

Performance scores use the same weighted metric formula as Google Lighthouse v10 — based on FCP, Speed Index, LCP, Total Blocking Time, and Cumulative Layout Shift. SEO and Accessibility scores are based on technical audits against established best practices (WCAG 2.1, search engine guidelines).

Built with

  • Go API backend with Chromium-based scanning
  • Next.js frontend
  • Chrome DevTools Protocol for metrics collection
  • PostgreSQL for report storage

Get in touch

PageDiag is built by Ryan. Have feedback or found a bug? Get in touch at hello@pagediag.com.