GZIP Compression Test
Check if a website uses GZIP or Brotli compression. See content-encoding headers and caching configuration.
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Why Compression Matters for Performance
Text-based resources like HTML, CSS, and JavaScript compress by 60-80% on average. Without compression, browsers download the full uncompressed payload over the network, resulting in slower page loads and higher bandwidth costs. Google uses page speed as a ranking signal, and uncompressed responses are one of the most common — and most easily fixable — performance bottlenecks. Enabling compression is typically a single server configuration change that immediately improves Time to First Byte and Largest Contentful Paint for every visitor.
GZIP vs Brotli vs Deflate
GZIP is the most widely supported compression algorithm, understood by every modern browser and supported by every major web server. Brotli, developed by Google, achieves 15-25% better compression ratios than GZIP at comparable CPU cost and is supported by all modern browsers over HTTPS. Deflate is the oldest algorithm and largely superseded by GZIP — it uses the same underlying algorithm but with a simpler wrapper, and some implementations have compatibility issues. For best results, configure your server to serve Brotli to browsers that support it and fall back to GZIP for the rest.
How to Enable Compression
- Apache: Add 'AddOutputFilterByType DEFLATE text/html text/css application/javascript application/json' to your .htaccess or virtual host configuration. For Brotli, enable mod_brotli and use 'AddOutputFilterByType BROTLI_COMPRESS' with the same content types.
- Nginx: Add 'gzip on; gzip_types text/html text/css application/javascript application/json;' to your server block. For Brotli, compile the ngx_brotli module and add 'brotli on; brotli_types text/html text/css application/javascript application/json;'.
- CDN (Cloudflare, Vercel, Netlify): Most CDN providers enable GZIP and Brotli compression by default for text-based content types. Check your CDN dashboard to confirm compression is active — some plans require explicit opt-in for Brotli.