Gzip and Brotli compression: how to check pages are sent compressed
Compression shrinks HTML, CSS and JavaScript before it is sent. Check that your store serves gzip or Brotli and fix a host that does not.
2 min read
Area
Store discovery
Severity
Medium
Fix effort
Small
Stores failing
0%
Of 35 stores we scanned where this check applies, 0% fail it and 100% pass. See all benchmarks.
Compression shrinks text files such as HTML, CSS and JavaScript before they travel over the network. Gzip and Brotli typically cut their size by well over half. Almost every hosted platform does this automatically, and a self-hosted store that skips it sends far more data than needed.
Why it matters
It is one of the cheapest speed improvements there is, and a missing setting is easy to miss. Pages feel slower, particularly on mobile data, and the cause is invisible unless you read the response headers.
What the audit looks at
The audit checks that your pages are sent compressed.
What usually causes it
- A web server or host with compression switched off
- A CDN or proxy setting that removes the compressed version
- A caching plugin that serves pages uncompressed
- Custom hosting that was never tuned
How to fix it
Turn on gzip or Brotli compression on your server or CDN. The effort is small, usually a setting or a paste and under 30 minutes.
- Enable gzip or Brotli for HTML, CSS and JavaScript at your host or CDN.
- Re-test: the response should carry a content-encoding header.
On Shopify
- Shopify compresses pages for you. If this shows as missing, a proxy or app in front of the store is stripping it: check what sits between visitors and Shopify.
On WooCommerce
- Enable gzip or Brotli in your caching plugin (WP Rocket, LiteSpeed Cache) or ask your host to turn it on.
How to check it yourself
- Open DevTools, go to Network, click the main document and read the content-encoding response header.
- Run your address through an online compression checker.
- Ask your host to confirm Brotli or gzip is enabled.
Frequently asked questions
Is Brotli better than gzip?
Brotli usually compresses text slightly better. Either is a large improvement over none.
Are images compressed this way?
No. Images are already compressed formats. Compression here applies to text files.
Related checks
Check your own store
See whether your store passes this check
Paste your store URL. The audit loads your pages in a real browser and shows the result for this check with the evidence behind it.