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The mime-types library provides a library and registry for information about MIME content type definitions. It can be used to determine defined filename extensions for MIME types, or to use filename extensions to look up the likely MIME type definitions.

MIME content types are used in MIME-compliant communications, as in e-mail or HTTP traffic, to indicate the type of content which is transmitted. The mime-types library provides the ability for detailed information about MIME entities (provided as an enumerable collection of MIME::Type objects) to be determined and used programmatically. There are many types defined by RFCs and vendors, so the list is long but by definition incomplete; don't hesitate to to add additional type definitions (see Contributing.rdoc). The primary sources for MIME type definitions found in mime-types is the IANA collection of registrations (see below for the link), RFCs, and W3C recommendations.

The mime-types library uses semantic versioning. This is release 2.0; there are incompatible changes in the API provided by mime-types, mostly around registry initialization (see History.rdoc for full details), and the removal of support for Ruby 1.8 interpreters.

mime-types (previously called MIME::Types for Ruby) was originally based on MIME::Types for Perl by Mark Overmeer, copyright 2001 - 2009. It is built to conform to the MIME types of RFCs 2045 and 2231. It tracks the IANA registry (ftp) with some unofficial types added from the LTSW collection and added by the users of mime-types.


MIME types are used in MIME entities, as in email or HTTP traffic. It is useful at times to have information available about MIME types (or, inversely, about files). A MIME::Type stores the known information about one MIME type.

require 'mime/types'

plaintext = MIME::Types['text/plain']
# returns [text/plain, text/plain]
text      = plaintext.first
puts text.media_type            # => 'text'
puts text.sub_type              # => 'plain'

puts text.extensions.join(" ")  # => 'txt asc c cc h hh cpp hpp dat hlp'

puts text.encoding              # => quoted-printable
puts text.binary?               # => false
puts text.ascii?                # => true
puts text.obsolete?             # => false
puts text.registered?           # => true
puts text == 'text/plain'       # => true
puts MIME::Type.simplified('x-appl/x-zip')
                                # => 'appl/zip'

puts MIME::Types.any? { |type|
  type.content_type == 'text/plain'
}                               # => true
puts MIME::Types.all?(&:registered?)
                                # => false

:include: Contributing.rdoc

:include: Licence.rdoc