SEO Report Tools

Website Audits · Live check · Free

Compression Checker (Gzip / Brotli)

Check whether a page is served with gzip or Brotli and how much it could shrink.

What this tool does

Reads Content-Encoding and Vary headers and estimates the potential saving for uncompressed text responses.

Who should use it

Developers and site owners tuning performance.

How it works

The request advertises supported encodings; the Content-Encoding response header is read. For uncompressed text, the body is gzip-compressed at level 6 to estimate savings.

How to use it

  1. Enter the full address of the page or site, including https://.
  2. Press the run button. The check makes live requests from our server and can take up to about 30 seconds.
  3. Read the findings first, then open the tables for detail. Each finding has a severity and a suggested fix.
  4. Copy or download the results if the tool offers it, fix the issues on your site and run the check again to confirm.

Practical example

A 120 KB HTML page without compression would save about 80% with gzip.

Understanding the results

No Vary: Accept-Encoding header can break shared caches.

Limitations

Different clients may receive different encodings. Only the HTML document is tested.

Accuracy and report transparency

Findings come from a real HTTP request made by our server. The result panel shows the checked URL, the UTC time of the check and the data source, and separates measured findings from limitations. We do not show random or sample metrics.

Privacy

The URL you enter is used only to make the request and is not stored in our database. Results may be cached for about ten minutes to limit repeat requests, and the checker blocks local and private network addresses. See the Privacy Policy.

Try these next

Page Size CheckerMeasure a page's HTML size and the sizes of the first 20 files it references.Cache-Control CheckerInspect caching headers of a page and up to 10 of its static files.CSS MinifierMinify CSS by removing comments, whitespace and redundant units.

Frequently asked questions

Gzip or Brotli?

Brotli is usually smaller; gzip is universally supported. Either is far better than none.

Is my data sent to your server?

The URL you enter is sent to our server so it can request that page. We do not store the page content or your results. Only an anonymous usage counter is kept, and short-lived cached results may be held for about ten minutes to reduce repeat requests.

How accurate are the results?

Findings are verified against the live HTTP response our server received at the time shown. They can differ from what Google or your visitors see, because of location, caching, JavaScript rendering or bot blocking.

Is this tool really free?

Yes. There is no account, limit or paid plan. The site is supported by advertising, which is disclosed on our Advertising Disclosure page.

References