Bernhard Kau

Kau-Boy’s OpenSearch is deprecated and will be removed from the plugin directory on July 29, 2023, 13 years after its first release. If you still want to use OpenSearch on your site, I recommend switching to <a href="https://de.wordpress.org/plugins/open-search-document/" rel="nofollow ugc">Open Search Document</a> which is still actively supported.
Integrates an OpenSearchDescription so that users can add your blog as a search location to their browsers. Your favicon will also be visible next to the search option in the browser.
You don’t need to setup any information. Just install and activate the plugin!

Kau-Boy's Opensearch

Integrates an OpenSearchDescription so that users can add your blog as a search location to their browsers. Your favicon will also be visible next to  …

Add OpenSearch standard support for search clients to your website implementing 
the <a href="http://www.opensearch.org/Specifications/OpenSearch/1.1" rel="nofollow ugc">OpenSearch Specification 1.1</a>.
This plugin also adds optional support for search engine word suggestions, 
retrieved from the tags used in your website.
The autodiscovery feature embeds a link to the OpenSearch Description (OSD) 
into the head code of your website, allowing the automatic detection for the 
clients that implement the same standard (e.g. Mozilla Firefox search bar).

WP OpenSearch

Add OpenSearch standard support for search clients to your website.

Kau-Boy's Opensearch vs WP OpenSearch