An open format is a file format for storing digital data,[1] defined by a published specification usually maintained by a standards organization, and which can be used and implemented by anyone. For example, an open format can be implemented by both proprietary and free and open-source software, using the typical software licenses used by each. In contrast to open formats, closed formats are considered trade secrets. Open formats are also called free file formats if they are not encumbered by any copyrights, patents, trademarks or other restrictions (for example, if they are in the public domain[1]) so that anyone may use the format at no monetary cost for any desired purpose.[2] However, the actual image used by an open format may still be copyrighted or trademarked.

Depending on the definition, the specification of an open format may require a fee to access or, very rarely, contain other restrictions.[2] The range of meanings is similar to that of the term open standard.

Specific definitions

Sun Microsystems

Sun Microsystems defined the criteria for open formats as follows:[1]

UK government

In 2012 the UK Government created the policy Open Standards Principles, stating that the Open Standards Principles apply to every aspect of government IT and that Government technology must remain open to everyone.[3] They have seven principles for selecting open standards for use in government, following these principals many open formats were adopted, notably Open Document Format (ODF). The seven principles for selecting open standards for use in the UK government are:

US government

Within the framework of Open Government Initiative, the federal government of the United States adopted the Open Government Directive, according to which: "An open format is one that is platform independent, machine readable, and made available to the public without restrictions that would impede the re-use of that information".[4]

State of Minnesota

The State of Minnesota defines the criteria for open, XML-based file formats as follows:[5]

Commonwealth of Massachusetts

The Commonwealth of Massachusetts "defines open formats as specifications for data file formats that are based on an underlying open standard, developed by an open community, affirmed and maintained by a standards body and are fully documented and publicly available."[6]

The Enterprise Technical Reference Model (ETRM) classifies four formats as "Open Formats":

  1. OASIS Open Document Format For Office Applications (OpenDocument) v. 1.1
  2. Ecma-376 Office Open XML Formats (Open XML)
  3. Hypertext Document Format v. 4.01
  4. Plain Text Format

The Linux Information Project

According to The Linux Information Project, the term open format should refer to "any format that is published for anyone to read and study but which may or may not be encumbered by patents, copyrights or other restrictions on use"[2] – as opposed to a free format which is not encumbered by any copyrights, patents, trademarks or other restrictions.

Examples of open formats

Main article: List of open formats

Open formats (in the royalty-free and free access sense) include:[2]

The following formats are open (royalty-free with a one-time fee on the standard):

See also


  1. ^ a b c Open Document Format for Office Applications (OpenDocument) v1.0 – OASIS Standard, 1 May 2005
  2. ^ a b c d "Free File Format Definition". Retrieved 11 February 2007.
  3. ^ a b "Open Standards principles". Gov.UK. 5 April 2018. Retrieved 10 September 2021.((cite web)): CS1 maint: url-status (link)
    Text was copied from this source, which is available under an Open Government Licence v3.0. © Crown copyright.
  4. ^ "Open Government Directive". The White House.
  5. ^ Meanwhile, Deep Down in Texas: An Open Format Bill is Filed – Tuesday, 6 February 2007 @ 03:55 PM PST Contributed by: Andy Updegrove –
  6. ^ Major Revision of Massachusetts Enterprise Technical Reference Model (ETRM). Robin Cover, Editor – Created: 3 July 2007. – Cover Pages