Despite a tough real estate market, Seattle upstart Redfin continues its march across the country.

The online real estate broker today announced that it has begun serving home buyers and sellers in Sacramento and parts of New York, including Westchester County and Long Island.

Redfin also said it is adding new information to its Web site -- including data about the seller's mortgage; number of days on the market for properties and pricing history -- as part of a settlement between the Department of Justice and the National Association of Realtors.

"More liberal data-sharing policies among listing services and a new partner-assisted strategy have opened a new phase of growth for Redfin," said Redfin CEO Glenn Kelman in a release. As part of the settlement between the DOJ and National Association of Realtors, listing services are now required to provide brokers with any information that brokers could disclose in-person.

Redfin, which refunds half of its broker's commission to home buyers, also operates service in Boston, Chicago, Seattle, Washington D.C., Baltimore, San Francisco and southern California. The company -- backed by Madrona Venture Group, Vulcan Ventures and others -- plans to expand into three new markets this year.

It is doing that by partnering with existing real estate agents in those markets, a strategy it is employing in Westchester County. Until recently, Redfin relied on its own agents to help customers buy and sell properties.