Why does compression matter?

A compressed response transfers far fewer bytes over the network, which speeds up page loads — an uncompressed text/HTML/JSON response on a production site is usually a missed easy win.

Does every response need to be compressed?

No — already-compressed formats (JPEG, PNG, MP4, WOFF2) gain little to nothing from further compression; this matters most for text-based responses (HTML, CSS, JS, JSON, SVG).

Compression Checker

Check whether a URL’s response is served compressed (gzip/brotli) and with what Vary header.

URL

The URL is fetched from our server (an arbitrary cross-origin fetch isn't possible directly from your browser) — the target site sees this server's request, not your IP, and nothing about the check is stored.

Related tools

HTTP Status Checker
Redirect Chain Viewer
URL Expander
HTTP Headers Checker

How it works

1
Enter a URL

Including the protocol.
2
Content-Encoding and Vary read

From the final response, after redirects.
3
See whether it’s compressed

And which encoding (gzip, br, deflate) is used.

FAQ

Why does compression matter?: A compressed response transfers far fewer bytes over the network, which speeds up page loads — an uncompressed text/HTML/JSON response on a production site is usually a missed easy win.
Does every response need to be compressed?: No — already-compressed formats (JPEG, PNG, MP4, WOFF2) gain little to nothing from further compression; this matters most for text-based responses (HTML, CSS, JS, JSON, SVG).