Website Compression Checker

Common compression problems

How to check website compression

1. Enter the URL of a page, stylesheet or script, for example https://example.com.
2. Click Check compression. We request it four times: asking for Brotli, gzip, zstd and no compression.
3. Read which encodings the server used, the size of each response and the percentage saved.
4. Turn on what is missing in your server or CDN, then check again.

Why compression matters for speed and SEO

Every page is downloaded before it can be shown. HTML, CSS and JavaScript are plain text with a lot of repetition, so gzip, Brotli and zstd can often shrink them to a fraction of their size. The browser lists the encodings it understands in the Accept-Encoding header, the server picks one and labels the response with Content-Encoding, and the browser unpacks it. Visitors notice nothing except that the page arrives sooner.

Page weight matters most on mobile. Phones are often on slower or congested connections and on metered data plans, where every extra megabyte costs time and money. An uncompressed page can easily be several times heavier than it needs to be.

Speed also feeds into how Google judges page experience. Core Web Vitals measure real visitors, and Largest Contentful Paint (LCP) is the time until the main content appears; Google treats 2.5 seconds or less as good. The browser cannot render a page until it has its HTML and the CSS that blocks rendering, so smaller text files can help LCP. Compression does not shrink images, which are often the LCP element, so it is one fix among several.

Be realistic about rankings. Google says it uses Core Web Vitals as part of its ranking systems, but relevance and content quality come first, and a fast page does not outrank a more useful one. Treat compression as removing a handicap, not as a ranking trick.

Crawling is the other side. Googlebot accepts gzip and Brotli, and Google says it crawls a site more when the server responds quickly. For most small sites crawl budget is not a concern, but large sites with many URLs benefit from every byte and millisecond saved.

# nginx
gzip on;
gzip_vary on;
gzip_types text/css application/javascript application/json image/svg+xml;

# request and response
Accept-Encoding: gzip, deflate, br, zstd
Content-Encoding: br
Vary: Accept-Encoding

When to use a compression checker

Check something else

• Website Response Time TestMeasure how long a website takes to respond, split into DNS, connect, TLS, server wait and download.
• Security Headers CheckerGrade a site's HTTP security headers (HSTS, CSP, X-Frame-Options and more) from A+ to F.
• Redirect CheckerTrace every redirect hop of a URL with status code, Location and time, and spot loops and long chains.
• HTTP Status Code CheckerCheck the HTTP status code any URL returns, with response time and every redirect on the way.

Frequently asked questions