Most Internet users have a favorite search engine, one that produces consistent, reliable and relevant results to their queries. For those who have Northern Light bookmarked, there's bad news today.

As of Jan. 16, the Cambridge, Mass., company will no longer offer free Web searches to the masses, focusing instead on large companies and government organizations (for example, today's CIA deal). Another large customer is Boston financial services giant Fidelity Investments.

"Over the past year, Northern Light has seen booming demand for search, classification, taxonomy, and content solutions from our enterprise customers and marketing partners," said David Seuss, Northern Light's CEO. "Meanwhile, the business model for free, advertising-supported, public Web search has not been developing for us."

Seuss said sales bookings for the quarter ended in December doubled over the previous quarter, however the growth came from corporate customers. The company is privately held and does not release detailed financial information.

The shift is one that companies in several Internet sectors are making as ad dollars peter out. For example Terra Lycos , which has its U.S. headquarters in Waltham, Mass., is charging for specialized content. Alta Vista, owned by Andover, Mass., investor CMGI is selling its search technology to companies with large databases to manage.

But the general public won't be left entirely in the dark. The company's Special Collection, an online business library of 70 million pages from 7,100 sources, will continue to be offered through its Web site.

Northern Light is venture-backed by former Microsoft executive Gregory Whitten and others. It was named after a 19th century sailing ship, that at the time, boasted an advanced design.