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Website Tools

Website Compression Checker

See whether your server compresses pages and how much it saves. The checker downloads the page three times – asking for Brotli, for gzip and for no compression – and reports the bytes actually transferred each time, the encoding the server used, the percentage saved and the Vary: Accept-Encoding header that caches need. It then checks the Content-Encoding of up to 20 of the page’s CSS and JavaScript files.

  • Encrypted connection
  • No sign-up
  • Free to use

How to use Website Compression Checker

  1. Enter the page address.
  2. Click “Check compression”.
  3. Compare uncompressed, gzip and Brotli sizes.
  4. Fix files served without compression.

Website Compression Checker features

Three measurements

Brotli, gzip, none.

Savings

In bytes and percent.

Assets

CSS and JavaScript encoding.

Vary header

Cache safety.

Measured, not guessed

Real transfer sizes from our server.

Safe fetching

Public addresses only, with size and time limits.

When to use Website Compression Checker

  • Speed audits.
  • Checking a new server or CDN.
  • Verifying web server settings.
  • Comparing hosting providers.

Website Compression Checker FAQ

Why does the server choose the encoding?

Browsers say which encodings they accept; the server picks one. Checking each encoding separately shows what it supports.

Should images be compressed with gzip?

No – JPEG, PNG, WebP and video are already compressed; gzip only helps text files.

How much should compression save?

HTML, CSS and JavaScript typically shrink by 70–90%.

Where do I turn it on?

In the web server (Apache mod_deflate/mod_brotli, Nginx gzip/brotli), hosting panel or CDN.

Website Brotli Checker Find out whether a site uses Brotli, the compression format that makes text files… Website Gzip Checker Test the most basic speed setting of a web server. The checker requests the page… Website Cache Checker See how well browsers and CDNs can cache your site. The checker reads the caching… Core Web Vitals Checker See how real visitors experience your page. Enter a URL and choose mobile or…

Why compression matters

Text compresses extremely well. A 500 KB HTML page can travel as 60 KB, which is a large difference on mobile connections.

Brotli usually beats gzip by 15–25% on text; most CDNs offer it with one switch.

How it works: our server downloads the page once through a guarded fetcher that only connects to public addresses, follows a limited number of redirects and stops after a size and time limit. The HTML is then analysed in your browser as inert text – scripts on the page never run and nothing is stored.

What it cannot see: content and resources that a page adds with JavaScript after it loads, pages behind a login, and servers that block automated requests. For those, open the page in your browser, use its developer tools, or paste the page source where the tool offers a paste option.

Use the results as a starting point: fix the items marked red first, review the yellow warnings in context, and run the check again after a change. Requests are rate-limited to keep the service fair; if you check many pages in a row, wait a few minutes.

Related checks on this site cover the rest of a technical review – speed and Core Web Vitals, security headers, structured data, accessibility and SEO signals – so you can work through a whole site audit one topic at a time.

Who it is for: site owners checking their own pages, developers debugging a release, SEO and marketing teams auditing clients or competitors, and students learning how the web works. No account or installation is needed, and the results are plain text and tables you can copy into a report or ticket.

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