Brotli Compression Checker

What one Brotli check observes

Enter one HTTP or HTTPS URL to request that resource with Brotli among the acceptable response encodings. The result reports whether that response’s Content-Encoding header includes br. HTTP distinguishes the request’s Accept-Encoding preferences from the response’s Content-Encoding, which tells the recipient what coding was applied. A server can choose a different representation or no compression, so the result describes this request and response only. The HTTP Semantics specification defines these headers; RFC 7932 specifies the Brotli compressed data format.

Read the status before the extra numbers

“Enabled” means the returned header contains br; “not enabled” means it does not. The page may also show the response’s encoding name and server header, plus a text-size estimate, a content length when available, an estimated percentage, and elapsed time. The result may also show text size, content length, an estimated percentage, and elapsed time.

Why a result can differ from another test

Compression can vary by resource, response headers, cache state, server configuration, and request context. A Brotli result for a homepage does not establish how its CSS, JavaScript, images, or API responses are encoded. A non-Brotli main document does not establish that every other resource lacks Brotli. Use this check as a quick inspection of one URL, then test representative resource URLs if you need to compare a site’s configuration.

Check a URL and interpret the response

1. Paste the complete address

   Include https:// or http:// and use the exact host and path you want to inspect.

2. Run the check

   The page makes a request that advertises support for common encodings including Brotli. A failed request produces an error rather than an enabled or disabled conclusion.

3. Read Content-Encoding

   Look for br in the returned content-encoding value. That is the direct signal used for the status. A value such as gzip, no encoding value, or another coding does not count as Brotli for this response.

4. Repeat on relevant resources

   If you are investigating a page, check the HTML and selected static assets separately. Compare runs under consistent URLs and conditions before drawing an operational conclusion.

Example of a narrow result

If https://example.com/ returns Content-Encoding: br, the observed response for that URL used Brotli. It does not prove every file on the domain does, and it does not by itself measure page load speed or the quality of a compression setting.

Scope and measurement questions

Limits of a header check

• Results can change with the URL, cache, proxy, server policy, and request context; they are a snapshot, not monitoring.
• The displayed compression percentage is only an estimate from available response information and text size, not an end-to-end transfer or speed benchmark. Missing content length, chunked responses, proxies, or automatic decoding can make sizes unavailable or incomparable.
• This is not a full performance audit and cannot measure user-perceived page speed, compression CPU cost, or site-wide coverage.
• Server identifiers may be absent or rewritten by intermediaries.
• Only submit a URL you are permitted to inspect. The result reports an HTTP response; it does not establish ownership or security of the destination.