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Using Gzip to compress MIME types (IANA media types) with Azion

Whenever a browser page is viewed, the webserver sends specific information regarding the page. Such details are in the page headers: they are important so the web browser can load and interpret the page.

In these cases, one of the headers is the Content-Type, responsible for processing and presenting the page content.

This sort of content is also called MIME type (Multipurpose Internet Mail Extensions), therefore determinant to define the type of document, files, or array of bytes, and how it should be processed.


A MIME type consists of a type and subtype. They are strings that, combined with a / symbol in between, will form the MIME type.

The type represents the category of that data file, whether it’s text or image. The subtype stands for exact data type represented by the MIME type. For instance, the MIME type image could be jpeg or png.

To compress images, use Azion’s Image Processor module for Edge Application. Read more

Even though it may look similar to a file extension, they are not the same. For example, a .png file will have image/png as a MIME type.

A MIME type will always have both extensions; that is, a type and a subtype.

So when your browser runs into an <img> tag, it sends out a request to the server, and if this image is a .png, the server will return with content-type: image/png.


To ensure a faster connection with your website, Azion provides files compression using Gzip. Smaller files result in faster downloads and faster page renderings for users.

When you set the Gzip behavior on Real-Time Manager’s Rules Engine, this is how the content is served:

  1. Azion will verify the cache for a compressed version of the file at the edge location.

  2. If the file is already compressed, it will be delivered to the viewer. If not, Azion will then compress the file, return it to the viewer, and add it to the cache.

  3. The viewer will decompress the file.

File types that Azion compresses:

MIME Type Extension Document Type
application/eot .eot MS Embedded OpenType fonts
application/font   OpenType font
application/font-sfnt .ttf
SFNT format
application/font-woff .woff Web Open Font Format (WOFF)
application/font-woff2 .woff2 Web Open Font Format 2 (WOFF2)
application/javascript .js JavaScript
application/json .json JSON format
application/ld+json .jsonld JSON-LD format
application/opentype .otf
application/otf .otf OpenType
application/truetype .ttf
application/ttf .ttf TrueType
application/vnd.ms-fontobject .eot MS Embedded OpenType fonts
application/x-font-opentype .otf OpenType
application/x-font-truetype .ttf TrueType
application/x-font-ttf .ttc
application/x-httpd-cgi .pl
CGI scripts/programs
application/x-javascript .js JavaScript
application/x-mpegurl .M3U8 iPhone Index
application/x-opentype .ttc OpenType font
application/x-otf .otf OpenType font
application/x-perl .plx
Perl script
application/x-ttf .ttf TrueType
application/xhtml+xml .xhtml XHTML
application/xml+rss .rss
RSS, Atom and XML
font/eot .eot Embedded Open Type
font/opentype otf
OpenType font
font/otf .otf OpenType font
font/ttf .ttf TrueType font
image/svg+xml .svg Scalable Vector Graphics (SVG)
image/x-icon .ico ICO
text/css .css Cascading Style Sheets (CSS)
text/csv .csv Comma-separated values (CSV)
text/html .htm
HyperText Markup Language (HTML)
text/javascript .js JavaScript
text/js .js JavaScript
text/plain .txt Text (generally ASCII or ISO 8859-n)
text/richtext .rtf Rich Text Format
text/tab-separated-values .tsv
Tab-separated values
text/x-component .htc HTML Components
text/x-java-source .jav Java Source
text/x-markdown .md Markdown
text/x-script .hlb HP OpenVMS
.xml XML

The entity responsible for all official MIME types is the Internet Assigned Numbers Authority (IANA)

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