Response Compression
Checks that HTML/CSS/JS responses are served with gzip or brotli compression.
What this check measures
We request the page with `Accept-Encoding: gzip, br` and verify the response includes `Content-Encoding: gzip` or `br`. Uncompressed text assets = 5-10x larger transfer.
Why it matters
Uncompressed HTML/JS/CSS slows down LCP on every page. Core Web Vitals suffer. Brotli cuts sizes ~70%; gzip ~65%. Free win on every modern host.
How our audit detects it
GET with Accept-Encoding header. Verify Content-Encoding in response. Compare compressed vs uncompressed size.
Typical findings
- error_outlineNo Content-Encoding header.
- error_outlineOnly gzip enabled, no brotli (modern browsers prefer brotli).
- error_outlineSelf-hosted setup without compression module enabled.
How to fix
Enable compression in your host's config. Vercel/Netlify/Cloudflare do this by default. Nginx/Apache: add `gzip on;` or `brotli on;` to config.
Copy-paste fix prompt for your stack
Lovable · Cursor · Bolt · v0 · Replit · Windsurf · Claude Code · Base44
Frequently asked questions
gzip or brotli?expand_more
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