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How to enable either Gzip or Deflate compression via .htaccess and which one is best these days? Code examples needed.

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3 Answers 3

See the Apache mod_deflate documentation, specifically, the "compress everything except images" example. It has worked well for me and would be put into an .htaccess file as follows:

<IfModule mod_deflate.c>
        # Insert filter
        SetOutputFilter DEFLATE

        # Netscape 4.x has some problems...
        BrowserMatch ^Mozilla/4 gzip-only-text/html

        # Netscape 4.06-4.08 have some more problems
        BrowserMatch ^Mozilla/4\.0[678] no-gzip

        # MSIE masquerades as Netscape, but it is fine
        # BrowserMatch \bMSIE !no-gzip !gzip-only-text/html

        # NOTE: Due to a bug in mod_setenvif up to Apache 2.0.48
        # the above regex won't work. You can use the following
        # workaround to get the desired effect:
        BrowserMatch \bMSI[E] !no-gzip !gzip-only-text/html

        # Don't compress images
        SetEnvIfNoCase Request_URI \
        \.(?:gif|jpe?g|png)$ no-gzip dont-vary

        # Make sure proxies don't deliver the wrong content
        Header append Vary User-Agent env=!dont-vary
</IfModule>

And, of course, make sure that you have the following in your httpd.conf file to enable mod_deflate:

LoadModule deflate_module libexec/apache2/mod_deflate.so
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I enabled deflate on static assets on my site (by MIME type) using the following added to the .htaccess file at the root of my public_html directory:

<ifModule mod_deflate.c>
  AddOutputFilterByType DEFLATE text/html text/xml text/css text/plain
  AddOutputFilterByType DEFLATE text/javascript application/javascript application/x-javascript application/json
</ifModule>

You can also enable it by file extension, though I don't have the syntax for that handy.

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up vote 4 down vote accepted

HTML5 Boilerplate (http://html5boilerplate.com) offers what seems to be the best and most effective solution setting along with plenty of others like caching, mime types etc. Highly recommended.

<IfModule mod_deflate.c>

# Force compression for mangled headers.
# http://developer.yahoo.com/blogs/ydn/posts/2010/12/pushing-beyond-gzipping
<IfModule mod_setenvif.c>
<IfModule mod_headers.c>
SetEnvIfNoCase ^(Accept-EncodXng|X-cept-Encoding|X{15}|~{15}|-{15})$ ^((gzip|deflate)\s*,?\s*)+|[X~-]{4,13}$ HAVE_Accept-Encoding
RequestHeader append Accept-Encoding "gzip,deflate" env=HAVE_Accept-Encoding
</IfModule>
</IfModule>


# Compress all output labeled with one of the following MIME-types
# (for Apache versions below 2.3.7, you don't need to enable `mod_filter`
#  and can remove the `<IfModule mod_filter.c>` and `</IfModule>` lines
#  as `AddOutputFilterByType` is still in the core directives).

<IfModule mod_filter.c>
AddOutputFilterByType DEFLATE application/atom+xml \
application/javascript \
application/json \
application/rss+xml \
application/vnd.ms-fontobject \
application/x-font-ttf \
application/x-web-app-manifest+json \
application/xhtml+xml \
application/xml \
font/opentype \
image/svg+xml \
image/x-icon \
text/css \
text/html \
text/plain \
text/x-component \
text/xml
</IfModule>

</IfModule>

EDIT: Since this question and answer keep getting upvoted after couple of years I'm putting H5BP server configs link for more complete optimization.

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