How to enable Brotli compression in Apache

Brotli compression reduces the size of HTML, CSS, JavaScript, JSON, XML, and SVG responses before Apache sends them to the client, which cuts bandwidth use and shortens transfer time on slower links.

Apache handles Brotli through mod_brotli. When a client advertises Accept-Encoding: br, the BROTLI_COMPRESS output filter compresses only the configured MIME types, then returns Content-Encoding: br and Vary: Accept-Encoding so caches keep compressed and uncompressed responses separate.

Current Debian and Ubuntu Apache packages already ship the mod_brotli module file and the brotli.load stub, so the job is usually enabling the built-in module and adding a conf-available rule set instead of building a third-party module. Compression still costs CPU and can contribute to BREACH-style side-channel exposure on HTTPS responses that reflect secrets, so keep the filter list focused on text responses that should be compressed.

1. Enable the built-in brotli module.

   $ sudo a2enmod brotli
   Enabling module brotli.
   To activate the new configuration, you need to run:
     systemctl restart apache2

   Current Debian and Ubuntu packages provide /usr/lib/apache2/modules/mod_brotli.so with apache2-bin and /etc/apache2/mods-available/brotli.load with apache2. There is no separate libapache2-mod-brotli package on current releases.

2. Create a Brotli rules file in /etc/apache2/conf-available/brotli.conf.

   $ sudo tee /etc/apache2/conf-available/brotli.conf >/dev/null <<'EOF'
   <IfModule mod_brotli.c>
       BrotliCompressionQuality 5
       BrotliAlterETag AddSuffix
       AddOutputFilterByType BROTLI_COMPRESS text/html text/plain text/css text/javascript application/javascript application/json application/xml text/xml application/xhtml+xml application/rss+xml application/atom+xml image/svg+xml
   </IfModule>
   EOF

   Keep the filter list on text-based responses. Formats such as JPEG, PNG, WebP, AVIF, ZIP, or MP4 are already compressed and usually waste CPU when passed through Brotli again.

3. Enable the Brotli configuration snippet.

   $ sudo a2enconf brotli
   Enabling conf brotli.
   To activate the new configuration, you need to run:
     systemctl reload apache2

4. Validate the Apache configuration syntax, then restart the service so the newly enabled module is loaded.

   $ sudo apachectl configtest
   Syntax OK
   
   $ sudo systemctl restart apache2

   Use a restart after a2enmod brotli. Later edits to only /etc/apache2/conf-available/brotli.conf can usually be applied with a reload instead.

   Related: How to test Apache configuration
   Related: How to manage the Apache web server service

5. Verify that mod_brotli is loaded.

   $ apachectl -M 2>/dev/null | grep brotli
    brotli_module (shared)

   apache2ctl -M returns the same module list on Debian and Ubuntu systems that prefer the apache2ctl wrapper name.

6. Confirm that a text response is served with Brotli compression.

   $ curl -sSI -H 'Accept-Encoding: br' -H 'Host: example.com' http://127.0.0.1/
   HTTP/1.1 200 OK
   Date: Wed, 08 Apr 2026 04:50:11 GMT
   Server: Apache/2.4.58 (Ubuntu)
   Last-Modified: Wed, 08 Apr 2026 04:50:09 GMT
   ETag: "29af-64eeba271beca-br"
   Accept-Ranges: bytes
   Vary: Accept-Encoding
   Content-Encoding: br
   Content-Length: 2722
   Content-Type: text/html

   If Content-Encoding: br is missing, test a text URL that matches the active virtual host. Binary assets and content types outside the AddOutputFilterByType list will not be compressed.