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
- Enter the page address.
- Click “Check compression”.
- Compare uncompressed, gzip and Brotli sizes.
- 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.
Why is the compressed size of my page almost the same as uncompressed?
Either compression is off for that content type, or the response is already compressed binary data. HTML, CSS and JavaScript usually shrink by 60–85%.
Should images be compressed by the server too?
No. JPEG, PNG, WebP and AVIF are already compressed; compressing them again wastes CPU and saves almost nothing. Compress text formats only.
Does compression slow down my server?
Barely. Compression uses little CPU compared with the bandwidth it saves, and static files can be compressed once in advance.
Comparing Brotli, gzip and none
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.
Downloading the same page three times – asking for Brotli, for gzip and for no compression – shows exactly what each option saves on your server. The result lists the encoding the server chose each time and the bytes transferred, so you can see whether Brotli is enabled at all and how much it adds over gzip.
The Vary: Accept-Encoding header tells caches and CDNs to store separate compressed and uncompressed copies. Without it, a cache may hand a Brotli-compressed file to a client that cannot read it, or an uncompressed file to everyone. Most servers add it automatically when compression is on; check it if you use a custom cache layer.
Up to 20 CSS and JavaScript files are checked as well. Static assets are ideal for pre-compression at the highest level during your build, because the server then sends a ready-made .br or .gz file without spending CPU on every request.
Compression is one of the cheapest speed wins: it is usually a single server or CDN setting and benefits every visitor. Check it after moving to a new host or adding a CDN, because default settings differ and compression can silently switch off. Make sure JSON responses from your API are compressed too.