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PerformanceChecked through WebDiag API

Page Weight Analyzer

Enter a page URL to get a bounded static HTML scan: HTML size, discovered img/script/link/source resources, known weight, heavy files, and modern image format signals.

  • Static HTML scan
  • Resource bytes
  • AVIF/WebP signals
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

    WebDiag loads HTML and safely inspects up to 40 discovered static resources.

  3. 3

    Review known bytes, unknown sizes, legacy images, and largest assets.

02

What the tool can do

  • Finds img/srcset/source/script/link/preload/icon/poster resources in HTML.
  • Detects resource types and modern image signals by content-type/URL.
  • Shows bounded scan mode so a static scan is not misrepresented as a full browser waterfall.
03

Common use cases

  • Quickly find heavy JPEG/PNG and JS/CSS assets before a full Lighthouse analysis.
  • Check whether AVIF/WebP variants are used for discovered images.
  • Evaluate baseline page weight after a release or theme change.
04

How it works inside

HTML body is capped by SafeHttpFetcher; resources are checked with read_body=false headers.

The tool does not replace the Core Web Vitals checker; it covers the fast resource summary layer.

05

Questions and answers

Why is this not a full waterfall?

A full waterfall requires a browser or PageSpeed. This is a safe fast static scan, so validation levels are not mixed.

Will it recommend AVIF/WebP?

Yes. Legacy JPEG/PNG heavy raster images are flagged as AVIF/WebP candidates, while SVG/PNG remain acceptable where justified.