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PerformanceChecked through WebDiag API

Core Web Vitals Checker

Run mobile, desktop, or both PageSpeed strategies to review Core Web Vitals, Performance, Accessibility, Best Practices, and SEO scores, plus prioritized checks to fix.

  • Google PageSpeed API
  • Mobile/Desktop
  • Lab + Field data
  • 4 Lighthouse categories
Online tool

Try the tool

Enter a URL: WebDiag will run a safe network check and show the result.

Network check through backend

For HTTP/SEO tools, the URL is sent to the WebDiag API, where SSRF protection, DNS/IP policy, and redirect limits are applied.

Reviewed: 2026-07-17
01

How to use it

  1. 1

    Paste a public page URL.

  2. 2

    Choose mobile, desktop, or both strategies.

  3. 3

    Review category scores, lab metrics, field data, and the ordered checks to fix.

02

What the tool can do

  • Backend Google PageSpeed API integration through GOOGLE_PAGESPEED_API_KEY env.
  • Separates Lighthouse lab metrics from Chrome UX field data when field data is available.
  • Shows four category scores and up to 20 failed or partial checks from their auditRefs.
  • Graceful unavailable state: missing key or provider errors never become a fake score.
03

Common use cases

  • Evaluate a landing page release before driving traffic.
  • Identify which Lighthouse opportunities provide the largest savings.
  • Separate lab issues from real Core Web Vitals field signals.
04

How it works inside

The frontend does not call Google directly: requests go through the WebDiag backend and normalized DTO.

Tests use mocked provider responses; real external calls do not run in the test suite.

05

Questions and answers

Why is there no result without an API key?

To avoid fake PageSpeed data. Production must set GOOGLE_PAGESPEED_API_KEY; without it WebDiag honestly shows an unavailable state.

Is field data always available?

No. Chrome UX field data is available only when there is enough real-user data for the URL or origin.