Gzip Compression Test

Check whether any public page uses gzip or Brotli compression, and see the exact transfer savings — measured, not guessed.

Or try an example:

Keep every page compressed — sitewide.

A single-page test is a start. SEOJuicer's full audit checks compression, meta tags, and more across every page on your domain, not just one URL.

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How it works

Test any page's compression in three steps

No signup, no install — just paste a URL and see exactly how much compression is saving you.

Enter a URL

Type in any public page you want to check — no signup needed.

We fetch it live

We measure the real transferred size against the uncompressed size.

See your savings

Get an exact compression percentage and which assets still aren't compressed.

Enable gzip or Brotli

Brotli typically compresses 15-20% smaller than gzip for the same content.

Compress every text asset

HTML, CSS, JS, JSON, and SVG all benefit — not just the main document.

Skip already-compressed files

Don't bother compressing JPGs, PNGs, or videos — they're already compressed and it wastes CPU.

FAQs

Frequently asked questions

Have questions about the gzip compression test? Here are the most common ones our users ask before getting started.

What does a gzip compression test actually measure?

It fetches the page and reads the Content-Encoding and Content-Length headers the server actually sent, then compares that against the real uncompressed byte count read from the response. That gives an exact, measured savings percentage rather than a guess — not every tool does this; some only check whether the header is present.

What's the difference between gzip and Brotli?

Both are compression algorithms for shrinking text-based responses before they're sent over the network. Brotli is newer and typically compresses 15-20% smaller than gzip for the same content, though gzip has slightly broader legacy client support. Most modern servers and CDNs support both.

Why would compression savings be 'unable to measure'?

Some servers send compressed responses using chunked transfer encoding without a Content-Length header, since the compressed size isn't known until the response finishes streaming. In that case we can confirm compression is enabled, but can't report an exact byte-for-byte savings percentage.

Should every file on my site be compressed?

No — only text-based files (HTML, CSS, JavaScript, JSON, SVG, XML) benefit meaningfully. Images, videos, and fonts are usually already compressed in their own format, so running gzip or Brotli on them again wastes CPU for little to no size reduction.

How much of a speed difference does compression really make?

For text-heavy pages, compression routinely cuts transfer size by 60-80%, which directly reduces download time — especially noticeable on slower mobile connections. It's one of the highest-impact, lowest-effort performance fixes available.

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