Gzip and Brotli Compression Checker
This free gzip compression checker requests your page three times, once without compression, once asking for gzip and once asking for Brotli, and compares the bytes that travel over the network. It shows which encodings your server supports, how much each saves, and the server setting to turn compression on if it is missing.
Gzip Compression Checker
Technical SEO
About this tool
Text files such as HTML, CSS, JavaScript and JSON compress very well. A server that supports gzip or Brotli sends a squeezed copy that the browser unpacks, so the same page downloads faster and uses less bandwidth. Compression is one of the cheapest speed improvements available, and a missing setting is common on new servers and some shared hosting.
The checker fetches your page with three different Accept-Encoding headers and measures the raw bytes received each time, without unpacking them. It compares the plain size with the gzip and Brotli sizes, reports the percentage saved, shows the Content-Encoding and Vary headers the server returned, and tells you what to change when compression is off.
Only the HTML document is tested, because that is the address you enter; static files such as stylesheets and scripts may be compressed differently, often by a CDN. Images, video and fonts in WOFF2 format are already compressed and should not be gzipped. Results may differ if a CDN serves a cached copy, so test the live address that visitors use.
Frequently asked questions
What is the difference between gzip and Brotli?
Both shrink text files before they are sent. Gzip is supported everywhere. Brotli usually produces smaller files for HTML, CSS and JavaScript but is only used over HTTPS and needs server or CDN support. Enabling both lets each browser pick the best one it understands.
How do I enable gzip compression?
On Nginx set gzip on and list the types to compress with gzip_types. On Apache enable mod_deflate and add AddOutputFilterByType DEFLATE text/html text/css application/javascript. Many hosts and CDNs, including Cloudflare, have a compression switch in their control panel.
Does compression help SEO?
Indirectly. Smaller responses load faster, and page speed feeds into Core Web Vitals and user experience, which Google uses in ranking. Compression alone will not lift rankings, but it removes a common reason for a slow first response on text-heavy pages.
Why does my site show no compression when my host says it is on?
Compression may be configured for some file types only, applied by a CDN after our request, or skipped for small responses. A security plugin or proxy can also strip the Accept-Encoding header. Check the Content-Encoding value shown in the result and the settings for the exact content types.