Google has launched a new service designed to let website publishers build their own search engines using Google’s massive index of page links.

The Google Custom Search Engine service will let anyone, from individuals to organisations, put a Google-powered search box on their sites that only searches certain sites and pages. That way, the publisher of a site about, say, hockey, could put a search box on his home page that only returns links to pages about hockey. The service will also let publishers have a search engine that taps Google’s index in full but gives preference to results from websites they have pre-selected.

With Custom Search Engine, Google joins others that provide similar services, including Yahoo and Rollyo. These custom engines are part of the social search concept, which taps users to refine the search engine experience by contributing, categorising, tagging and sharing search results. For example, site publishers using the Google service can let others contribute to their custom index.

Designed to be extremely easy and intuitive to use, the service will let site publishers build their own search engine in a matter of minutes through the use of menus and wizards, said Marissa Mayer, Google’s vice president of search products and user experience.

The service is hosted on Google servers, so site publishers don’t get access to search query logs, a sensitive topic for users who are concerned about the privacy of their search activities. However, the entire search experience happens in the publishers’ sites, and they can personalise the search results page so that its layout is in tune with the rest of their pages, Mayer said. Google will display contextual ads with search results, but sites run by government agencies, nonprofit organisations and universities can opt out of this.

Google stands to benefit not only from sharing ad revenue with publishers but also from propagating the availability of its search engine, analyst Greg Sterling of Sterling Market Intelligence said. “People are doing searches on all kinds of sites, not just search engines,” he said. “Search has become the Web’s navigational paradigm.”

Meanwhile, there is considerable demand from publishers for custom search engines because they realise that providing that capability makes their websites more attractive to their visitors, Sterling said.