Sada Files
  1. 1Choose file
  2. 2Adjust
  3. 3Download

Check a public page

Enter a URL in the settings and run the check. Our server fetches the page through an SSRF-safe fetcher, analyses it in memory and stores nothing.

Fetched by our server — public addresses only, nothing stored or logged.

Render-Blocking Resource Detector online, free

Identify critical CSS stylesheets and synchronous scripts in HTML head blocking the browser's first contentful paint.

  • Runs in your browser — no upload
  • Free, no sign-up, no watermark
  • HTML
  • TXT
How to use Render-Blocking Resource Detector · Render-Blocking Resource Detector — frequently asked questions

How to use Render-Blocking Resource Detector

  1. 1

    Add your HTML and TXT file

    Drop a file on the page, paste it, or click Select Files. Nothing is uploaded — it opens straight in your browser.

  2. 2

    Fine-tune the settings

    Set source mode in the Fine-tune panel, or keep the defaults — they suit most files.

  3. 3

    Run Render-Blocking Resource Detector

    Press the start button. Processing happens on your device, usually in seconds.

  4. 4

    Download the result

    Save the finished file, or continue with another tool without downloading in between.

What Render-Blocking Resource Detector can do

  • Source Mode: url and paste
  • Private by design — files are processed in your browser and never uploaded
  • Free with no sign-up, no watermark and no daily limit

Render-Blocking Resource Detector — frequently asked questions

What are render-blocking resources?

Render-blocking resources are external stylesheets (`<link rel="stylesheet">`), web fonts, and synchronous script tags (`<script src="...">`) that prevent the browser from rendering visible pixels until they are completely downloaded and parsed.

How do render-blocking files affect Google Core Web Vitals?

Render-blocking scripts and styles directly delay First Contentful Paint (FCP) and Largest Contentful Paint (LCP), two primary Core Web Vitals metrics that impact search rankings and bounce rates.

What strategies does the tool recommend to eliminate render-blocking assets?

The tool recommends adding `async` or `defer` attributes to non-essential JavaScript, using native ES modules (`type="module"`), preloading critical assets with `<link rel="preload">`, and inlining critical above-the-fold CSS while deferring full stylesheets.

Can I inspect render-blocking code from local or staging templates?

Yes. Select Paste mode and paste your template `<head>` or complete page HTML to inspect all blocking scripts and stylesheets entirely client-side.

Does this tool track or save the URLs or code inspected?

No. Sada Files enforces a strict privacy promise: all analyses execute statelessly without logging URLs, IP addresses, or audited code.

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