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gzip/Brotli Compression Checker

Check if compression is enabled on your site to speed up page loading

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This only checks compression. For a comprehensive analysis, use the full page check.

You can also audit your entire site. Duplicate titles and descriptions, orphan pages, broken links between sections, and other site-wide issues can only be found with a full site audit.

If you don't have an SEO specialist, we can help fix the errors found.

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Why gzip and Brotli Compression Matters

Compression is one of the most effective ways to speed up your site. When the server delivers HTML, CSS, and JavaScript in compressed form, the data transferred is reduced by 3-10x. The browser receives the compressed response and decompresses it instantly. Users see the page faster, and the server uses less bandwidth.

What This Tool Checks

  • Content-Encoding header — presence of gzip or br (Brotli) in the server response
  • Compression type — which algorithm is used: gzip, Brotli, or deflate
  • Size before and after compression — how effectively the page is compressed
  • Compression ratio — percentage of bandwidth savings during data transfer
  • Vary header — proper caching configuration for compressed responses

Difference Between gzip and Brotli

  • gzip — classic compression algorithm, supported by all browsers, compresses text resources by 70-80%
  • Brotli (br) — modern algorithm by Google, compresses 15-25% better than gzip, supported by all modern browsers
  • Compatibility — Brotli only works over HTTPS, gzip works over any protocol
  • Recommendation — use Brotli as primary with gzip fallback for older clients

How to Enable Server Compression

  • Nginx — gzip on; and brotli on; directives in server config
  • Apache — mod_deflate (gzip) and mod_brotli modules to enable compression
  • CDN — Cloudflare, AWS CloudFront, and other CDNs automatically compress content
  • Node.js — compression (gzip) and shrink-ray-current (Brotli) middleware for Express

Frequently Asked Questions

Which is better — gzip or Brotli? ▶
Brotli compresses 15-25% more effectively than gzip and is supported by all modern browsers. However, Brotli only works over HTTPS. The best strategy is to configure Brotli as the primary algorithm and keep gzip as a fallback for clients that don't support Brotli. This gives you maximum compression for most users.
Does compression affect SEO? ▶
Yes, indirectly. Compression speeds up page loading, and speed is one of Google's ranking factors. Without compression, a 200 KB page is transferred in full, but with gzip only 30-50 KB. This directly affects Core Web Vitals metrics, especially LCP and FCP, which Google considers for ranking.
Should images be compressed via gzip? ▶
No. Images in JPEG, PNG, WebP, and AVIF formats are already compressed. Attempting to compress them via gzip or Brotli won't help and will only waste CPU. Compression should be enabled for text resources: HTML, CSS, JavaScript, JSON, XML, SVG. These are where compression provides maximum bandwidth savings.

Other Checks

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robots.txt Check
sitemap.xml Check
SSL Certificate Check
HTTP/HTTPS Check
www Redirect Check
Title Tag Check
Meta Description Check
Headings Check
Canonical Check
Viewport Check
Open Graph Check
Encoding Check
Image Format Check
Alt Tags Check
Lazy Loading Check
Internal Links Check
External Links Check
Broken Links Check
Structured Data Check
Compression Check
HTML Size Check
Render-blocking JS Check
Mixed Content Check
HSTS Check
URL Structure Check