|Initial release||March 15, 2005|
|Latest release||1.1 / December 6, 2005|
|Type of format||Web syndication|
|Open format?||Creative Commons Attribution-ShareAlike 2.5 License|
OpenSearch is a collection of technologies that allow publishing of search results in a format suitable for syndication and aggregation. It is a way for websites and search engines to publish search results in a standard and accessible format.
OpenSearch was developed by Amazon.com subsidiary A9 and the first version, OpenSearch 1.0, was unveiled by Jeff Bezos at the O'Reilly Emerging Technology Conference 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 Attribution-ShareAlike 2.5 License.
OpenSearch consists of:
- OpenSearch Description files: XML files that identify and describe a search engine.
- OpenSearch Query Syntax: describe where to retrieve the search results
- OpenSearch RSS (in OpenSearch 1.0) or OpenSearch Response (in OpenSearch 1.1): format for providing open search results.
- OpenSearch Aggregators: Sites that can display OpenSearch results.
- 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 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 <link> 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.
OpenSearch is not limited to search functionality. It can be used to pass user-submitted variables from the client browser:
See also 
- OpenSearch.org – official website, including specifications