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Compression Performance

Brotli Compression Test

Check if any website supports Brotli compression. Compare Brotli vs Gzip transfer sizes, measure bandwidth savings, and view server compression headers.

  • Instant Brotli (br) detection
  • Brotli vs Gzip size comparison
  • Bandwidth savings calculator

Compression optimization

Speed up your site with modern compression

Practical context to help you turn the output into faster, more reliable experiences.
01

Why Brotli outperforms Gzip

Brotli is an open-source data format developed by Google specifically optimized for web content. Unlike Gzip, which relies purely on general-purpose DEFLATE compression, Brotli includes a built-in static dictionary containing over 13,000 common HTML tags, CSS rules, and JavaScript patterns.

This specialized dictionary allows Brotli to compress text assets 14% to 25% smaller than standard Gzip, resulting in smaller payloads, faster mobile downloads, and reduced CDN bandwidth expenses.

02

Impact on performance and Core Web Vitals

Asset transfer size directly affects key web performance metrics. Delivering smaller HTML documents speeds up Time to First Byte (TTFB) and First Contentful Paint (FCP), while compressed CSS and JavaScript bundles unblock the browser rendering pipeline earlier.

Modern CDNs like Cloudflare, Fastly, and CloudFront, as well as web servers like Nginx and Caddy, support automatic Brotli compression. Use this tool to verify that your server correctly advertises and delivers the content-encoding: br response header.

Frequently Asked Questions

Q. What is Brotli compression and how does it work?

Brotli is an open-source lossless data compression algorithm developed by Google. It combines a 2nd-order context modeling algorithm, LZ77 window, and Huffman coding, alongside a built-in static dictionary of over 13,000 common words and HTML/CSS/JS fragments to achieve higher compression ratios than Gzip.

Q. How much smaller is Brotli compared to Gzip?

On average, Brotli produces file sizes 14% to 25% smaller than Gzip for HTML, JavaScript, and CSS assets. For JavaScript bundles, Brotli typically compresses 17% smaller, and for CSS styles, 20% smaller than standard Gzip level 6.

Q. Which browsers support Brotli compression?

Brotli is supported by over 97% of all web browsers globally, including Chrome, Safari, Edge, Firefox, and Opera. Browsers advertise support automatically by sending the "Accept-Encoding: br" request header over HTTPS connections.

Q. How do I enable Brotli on my web server or CDN?

On Cloudflare or Fastly, Brotli can be enabled with a single toggle in your dashboard under Speed/Optimization settings. On Nginx, enable the ngx_brotli module with "brotli on;". On Apache, enable mod_brotli with "AddOutputFilterByType BROTLI_COMPRESS". Caddy web server enables Brotli natively by default.

Q. Does Brotli compression improve Core Web Vitals?

Yes. By reducing HTML, CSS, and critical JavaScript transfer payload sizes, Brotli directly reduces page download time and network transfer latency, improving Largest Contentful Paint (LCP) and First Contentful Paint (FCP).