Gzip Compression Test: Check Gzip Compression
Gzip compression test that lets you check gzip compression (and Brotli) for any URL. See encoding, size before/after, and savings.
How it works
We request the URL server-side with Accept-Encoding: gzip, deflate, br and read the Content-Encoding response header, then compare the bytes on the wire against the decompressed size to show the real saving. This runs on our server because browsers are not allowed to set Accept-Encoding or read Content-Encoding from JavaScript.
How to use the Gzip / Brotli Compression Test
- 1Paste any URL into the input above.
- 2Click Test to fetch the response headers.
- 3See whether the server returned gzip, Brotli, or no compression.
- 4Get the recommended fix if compression is missing.
What you can do with the Gzip / Brotli Compression Test
Check if gzip is enabled on a URL.
Confirms whether your origin or CDN is gzipping text assets.
Check if Brotli is enabled.
Brotli typically saves 15–25% more than gzip on the same file, worth confirming you're shipping it.
Test compression on a single asset.
Paste the URL of a specific .js or .css file to verify it's compressed in transit.
Diagnose missing compression on WordPress.
If results show no encoding header, enable gzip in your caching plugin or at the CDN.
Gzip / Brotli Compression Test FAQs
What's the difference between gzip and Brotli?+
Both are HTTP compression algorithms. Brotli is newer and compresses text assets ~15–25% better than gzip at similar CPU cost. All modern browsers support both.
Is this safe? Do you store my URL?+
No. We make a single read-only request to fetch response headers, nothing is stored or shared.
Why does my site show no compression?+
Either your origin server isn't compressing text assets, or your CDN is stripping the Accept-Encoding header. Enable gzip/Brotli at the CDN or web-server level.
Should images be compressed with gzip?+
No. Images (JPG, PNG, WebP, AVIF) are already compressed, gzipping them wastes CPU and saves nothing.
How much faster will my site be with Brotli?+
Text assets typically shrink 70–85% in transit, which speeds up first paint noticeably on slow connections.
Want your whole site this fast? Our team offers full website speed optimization, done for you .