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• Plesk for Linux

Question

How to enable gzip compression in Apache?


Answer

Note: Since Plesk Obsidian 18.0.33 it is possible to use BROTLI compression which is considered to be better compression than GZIP.


                            Enabling per-domain using Plesk interface

Note: In case Smart static files processing is enabled in Domains > example.com > Apache & nginx Settings, disable it, or use the following article instead: How to enable gzip compression in nginx on a Plesk server

1.Log into Plesk

2.Make sure that 'deflate' and 'filter' modules ('filter' might be absent on CentOS 6) are enabled in Tools & Settings > Apache Web Server.

(https://pix.cobrasoft.org/images/2025/12/15/Untitled.png)

3.Go to Domains > example.com > File Manager and open the .htaccess file.

4.Add the following content to the bottom of the file:

<IfModule mod_deflate.c>
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
AddOutputFilterByType DEFLATE application/x-font
AddOutputFilterByType DEFLATE application/x-font-opentype
AddOutputFilterByType DEFLATE application/x-font-otf
AddOutputFilterByType DEFLATE application/x-font-truetype
AddOutputFilterByType DEFLATE application/x-font-ttf
AddOutputFilterByType DEFLATE application/x-javascript
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE font/opentype
AddOutputFilterByType DEFLATE font/otf
AddOutputFilterByType DEFLATE font/ttf
AddOutputFilterByType DEFLATE image/svg+xml
AddOutputFilterByType DEFLATE image/x-icon
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/javascript
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/xml

BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4\.0[678] no-gzip
BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
Header append Vary User-Agent
</IfModule>
(https://pix.cobrasoft.org/images/2025/12/15/Untitled-1.png)


                      Enable server-wide gzip compression using SSH connection

Note: In case Smart static files processing is enabled on domain in Domains > example.com > Apache & nginx Settings, disable it, or use the following article instead: How to enable gzip compression in nginx on a Plesk server

Note: On Debian and Ubuntu the service is named apache2 instead of httpd, the list of all modules is called using apache2ctl utility and the path for deflate.conf file is /etc/apache2/mods-available/ instead of /etc/httpd/conf.d/

1.Connect to the server via SSH

Note: if direct SSH access to the server is not possible, contact server administrator for further assistance.

2.Make sure that module mod_deflate is enabled in apache:

# httpd -M | grep deflate
deflate_module (shared)

3.Create a file deflate.conf in /etc/httpd/conf.d:

# vi /etc/httpd/conf.d/deflate.conf

4.Add the following into the file:

<IfModule mod_deflate.c>
# Compress HTML, CSS, JavaScript, Text, XML and fonts
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
AddOutputFilterByType DEFLATE application/x-font
AddOutputFilterByType DEFLATE application/x-font-opentype
AddOutputFilterByType DEFLATE application/x-font-otf
AddOutputFilterByType DEFLATE application/x-font-truetype
AddOutputFilterByType DEFLATE application/x-font-ttf
AddOutputFilterByType DEFLATE application/x-javascript
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE font/opentype
AddOutputFilterByType DEFLATE font/otf
AddOutputFilterByType DEFLATE font/ttf
AddOutputFilterByType DEFLATE image/svg+xml
AddOutputFilterByType DEFLATE image/x-icon
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/javascript
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/xml
# Remove browser bugs (only needed for really old browsers)
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4.0[678] no-gzip
BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
Header append Vary User-Agent
</IfModule>
5.Note in case of Centos OS, if the server has Apache 2.4 (httpd-2.4), the following module should be enabled:

# grep -ir "mod_filter.so" /etc/httpd/conf.modules.d/00-base.conf
LoadModule filter_module modules/mod_filter.so

In case of Debian and Ubuntu, check that the filter_module is enabled:

# apachectl -M | grep filter
filter_module (shared)

6.Restart Apache:

# service httpd restart