OpenSearch is a collection of technologies that allow publishing of search results in a format suitable for syndication

Web syndication

Web syndication is a form of syndication in which website material is made available to multiple other sites. Most commonly, web syndication refers to making web feeds available from a site in order to provide other people with a summary or update of the website's recently added content...

 and aggregation

Search aggregator

A search aggregator is a type of metasearch engine which gathers results from multiple search engines simultaneously through RSS search results...

. It is a way for website

Website

A website, also written as Web site, web site, or simply site, is a collection of related web pages containing images, videos or other digital assets. A website is hosted on at least one web server, accessible via a network such as the Internet or a private local area network through an Internet...

s and search engine

Search engine

A search engine is an information retrieval system designed to help find information stored on a computer system. The search results are usually presented in a list and are commonly called hits. Search engines help to minimize the time required to find information and the amount of information...

s to publish search results in a standard and accessible format.

OpenSearch was developed by Amazon.com

Amazon.com

Amazon.com, Inc. is a multinational electronic commerce company headquartered in Seattle, Washington, United States. It is the world's largest online retailer. Amazon has separate websites for the following countries: United States, Canada, United Kingdom, Germany, France, Italy, Spain, Japan, and...

 subsidiary A9

A9.com

A9.com is a subsidiary of Amazon.com based in Palo Alto, California that develops search engine technology. A9 currently has over 100 employees in its Palo Alto, Bangalore, and Dublin offices.A9 has worked in 3 areas over the years....

 and the first version, OpenSearch 1.0, was unveiled by Jeff Bezos

Jeff Bezos

Jeffrey Preston "Jeff" Bezos is the founder, president, chief executive officer , and chairman of the board of Amazon.com.-Early life and background:...

 at the O'Reilly Emerging Technology Conference

Emerging Technology Conference

The O'Reilly Emerging Technology Conference is O'Reilly Media's premier conference about the new technologies that are on the O'Reilly Radar. O'Reilly defines its core business not as books, conferences, or online publishing, though it does all three, but as "changing the world by spreading the...

 in March, 2005. Draft versions of OpenSearch 1.1 were released during September and December 2005. The OpenSearch specification is licensed by A9 under the Creative Commons

Creative Commons

Creative Commons is a non-profit organization headquartered in Mountain View, California, United States devoted to expanding the range of creative works available for others to build upon legally and to share. The organization has released several copyright-licenses known as Creative Commons...

 Attribution-ShareAlike 2.5 License.

Design

OpenSearch consists of:

1. OpenSearch Description files: XML
   Extensible Markup Language
   Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
   
    files that identify and describe a search engine.
2. OpenSearch Query Syntax: describe where to retrieve the search results
3. OpenSearch RSS
   RSS (file format)
   RSS is a family of web feed formats used to publish frequently updated works—such as blog entries, news headlines, audio, and video—in a standardized format...
   
    (in OpenSearch 1.0) or OpenSearch Response (in OpenSearch 1.1): format for providing open search results.
4. OpenSearch Aggregator
   Search aggregator
   A search aggregator is a type of metasearch engine which gathers results from multiple search engines simultaneously through RSS search results...
   
   s: Sites that can display OpenSearch results.
5. OpenSearch "Auto-discovery" to signal the presence of a search plugin link to the user and the link embedded in the header of HTML pages

OpenSearch Description Documents list search result responses for the given website/tool. Version 1.0 of the specification only allowed one response, in RSS format; however, version 1.1 provides support for multiple responses, which may be in any format. RSS and Atom

Atom (standard)

The name Atom applies to a pair of related standards. The Atom Syndication Format is an XML language used for web feeds, while the Atom Publishing Protocol is a simple HTTP-based protocol for creating and updating web resources.Web feeds allow software programs to check for updates published on a...

 are the only ones formally supported by OpenSearch aggregators, however other types, such as HTML are perfectly acceptable.

• Reference to the OpenSearch Description Document must be made in the root file of the domain.

e.g. for xyz.com the reference to the OpenSearch Description should be placed in xyz.com/index.html

Thus one domain can have only one Open Search reference.

• OpenSearch Description Document must be placed on a web server of the same domain.

Search engines and software that support OpenSearch

• Alfresco
  Alfresco (software)
  Alfresco is a Free/Libre enterprise content management system for Microsoft Windows and Unix-like operating systems. Alfresco comes in two flavours. Alfresco Community Edition is free software, LGPL licensed open source and open standards. Alfresco Enterprise Edition is commercially & proprietary...
  
  
• Arora
  Arora (browser)
  Arora is a free and open source lightweight cross-platform web browser. It runs on Linux, Mac OS X, Windows, FreeBSD, OS/2, Haiku, and any other platforms supported by the Qt toolkit....
  
  
• Bing API
• GNOME Do
  GNOME Do
  GNOME Do is a popular, free application launcher for Linux originally created by David Siegel, and currently maintained by Alex Launi...
  
   application launchers
• GNOME Shell in overview mode
• Google Chrome
  Google Chrome
  Google Chrome is a web browser developed by Google that uses the WebKit layout engine. It was first released as a beta version for Microsoft Windows on September 2, 2008, and the public stable release was on December 11, 2008. The name is derived from the graphical user interface frame, or...
  
  
• Internet Explorer 7
  Internet Explorer 7
  Windows Internet Explorer 7 is a web browser released by Microsoft in October 2006. Internet Explorer 7 is part of a long line of versions of Internet Explorer and was the first major update to the browser in more than 5 years...
  
   and above integrate web search services with their search bars.
• Mozilla Firefox 2
  Mozilla Firefox 2
  Mozilla Firefox 2 was a version of Firefox, a web browser released on October 24, 2006 by the Mozilla Corporation.Firefox 2 uses version 1.8 of the Gecko layout engine for displaying web pages...
  
   and above implement OpenSearch, as well as a subset named MozSearch. MozSearch is not intended for web use, only for Firefox related projects. Extended features from MozSearch are usable in an OpenSearch file with an XML namespace
  XML Namespace
  xmlns tagged XML namespaces are used for providing uniquely named elements and attributes in an XML document. They are defined in a W3C recommendation. An XML instance may contain element or attribute names from more than one XML vocabulary...
  
   prefix. Features specific to MozSearch include search suggestions, among others.
• Rekonq
  Rekonq
  rekonq is a lightweight, QtWebKit-based web browser developed inside the free software project KDE. It is the default web browser in Kubuntu 10.10 and Chakra GNU/Linux.rekonq has been officially included into KDE Extragear the 2010-05-25...
  
   0.7 and above.
• SAP NetWeaver Enterprise Search 7.2 and above supports the OpenSearch standards for search client and search provider plus some SAP-specific extensions
• SeaMonkey
  SeaMonkey
  SeaMonkey is a free and open source cross-platform Internet suite. It is the continuation of the former Mozilla Application Suite, based on the same source code...
  
   internet suite 2.1 Beta and above supports OpenSearch plugins as the default for web search.
• Search2.net
  Search2.net
  Search2.net is a search engine with an international index that is built on Nutch and online since 2009.Search2.net is located on server in Israel and has currently 5 million sites indexed.The search engine supported the OpenSearch description....
  
   support OpenSearch
• Wikipedia
  Wikipedia
  Wikipedia is a free, web-based, collaborative, multilingual encyclopedia project supported by the non-profit Wikimedia Foundation. Its 20 million articles have been written collaboratively by volunteers around the world. Almost all of its articles can be edited by anyone with access to the site,...
  
   suggests articles matching a typed-in entry with incremental find
  Incremental find
  In computing, incremental search, incremental find or real-time suggestions is a user interface interaction method to progressively search for and filter through text. As the user types text, one or more possible matches for the text are found and immediately presented to the user...
  
  .
• Windows 7 and Microsoft Search Server
  Microsoft Search Server
  Microsoft Search Server is an enterprise search platform from Microsoft, based on the search capabilities of Microsoft Office SharePoint Server. MSS shares its architectural underpinnings with the Windows Search platform for both the querying engine as well as the indexer...
  
   to let users federate searches to web services via a centralized location. (Note that even if the Site does not support OpenSearch, through a service on the "Find More Providers" page, one can add a website with a search engine if "TEST" is searched and the URL of the search page contains "TEST".)
• Microsoft SharePoint 2007 and SharePoint 2010