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How to Compress Websites with Gzip Compression

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Compressing your website pages on the server is a great way to improve your site speed overall. One site I manage was six times smaller after I enabled gzip compression.

Most modern browsers support compression of HTML, CSS, and JavaScript files. So if you set up your web server to deliver compressed files the majority of your readers will receive compressed files, greatly improving their delivery speed.

Difficulty: Average
Time Required: 15 minutes

Here's How:

  1. First, make sure that your site isn’t already being compressed by your hosting provider. Some hosting providers automatically compress HTML documents for their customers. To verify, use a tool like GIDZipTest to check your site. If it comes back with "Yes" then you’re done.

    Chances are that your pages are not compressed. And in order to compress them you need to have the following:

    • Know what server you are running (IIS or Apache or something else)
    • Access to your web server configuration
  2. For IIS

    If your server is IIS, follow the instructions in Microsoft TechNet document to enable compression.

    For Apache

    Edit your .htaccess file and add the following lines:

    # compress text, HTML, JavaScript, CSS, and XML
    AddOutputFilterByType DEFLATE text/plain
    AddOutputFilterByType DEFLATE text/html
    AddOutputFilterByType DEFLATE text/xml
    AddOutputFilterByType DEFLATE text/css
    AddOutputFilterByType DEFLATE application/xml
    AddOutputFilterByType DEFLATE application/xhtml+xml
    AddOutputFilterByType DEFLATE application/rss+xml
    AddOutputFilterByType DEFLATE application/javascript
    AddOutputFilterByType DEFLATE application/x-javascript
    # remove browser bugs
    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
  3. After you’ve saved the .htaccess file, test your site again in GIDZipTest. It should come up as compressed.

    If It Still Isn’t Compressed

    Some virtual hosts don’t always recognize output filters that are loaded in the .htaccess file. If your site isn’t compressed after adding those lines, then you’ll need to add them to the vhosts.conf or httpd.conf file for your site.

    Look for your site in the file and find the line that starts <Directory>. Then add the above lines into that section of the conf file, above the </Directory> line. Once you’ve saved the file, you’ll need to reload Apache.

    If it still isn’t compressed or you can’t edit the vhosts.conf or httpd.conf files, you’ll need to talk to your hosting provider about turning on compression.

What You Need

  • Access to .htaccess files or server administration files
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