Hoping to leave an even bigger imprint on the Internet, Google Inc. is opening up its vast online index so other Web sites can build their own specialty search engines.
The free service, unveiled late Monday, marks Google's latest attempt to expand its lucrative online advertising network and extend its influence on how people navigate the Internet.
"Now people can get the power of Google search even when they're not on Google.com," said Shashi Seth, group product manager for the custom search engine.
Mountain View-based Google already dominates Internet search, with a 45 percent share of the U.S. market through September, according to comScore Media Metrix.
The custom tools will allow other Web sites to limit the range of material that they want to include in their search indexes as well as rank the importance of specific pages.
The concept mirrors the approach of a small startup called Rollyo.com.
Google said it simplified the process so even technological neophytes should be able to tailor their own search engines in 10 minutes or so.