The Best Online Tools for Your Housing Search

There was a time when the only way to find homes for sale was to engage a real estate agent to send you listings or drive up and down the streets scouting "for sale" signs.

In the past decade, an explosion of online real estate listings services has drastically changed the way Americans look for homes. It's now possible, with a click of a mouse, to find the sales price of the home next door, search for listings in a given school zone and take virtual tours of homes you're interested in.

With the multiple listing service (or a reasonable facsimile) at their fingertips, most would-be buyers these days send listings to their agents rather than the other way around.

Home shoppers can look at homes for sale at realtor.com, Zillow, Trulia, Redfin or your agent's website, among other sources. In some cities, the local multiple listing service includes a consumer website.

And yes, there's an app for that. All the major services have mobile apps, and you can get text alerts and type notes on your phone as your significant other drives by. Some apps show you houses you may like based on your searches and those you've already looked at.

[Read: How to Compete in a Seller's Housing Market.]

This surge of online information has not eliminated real estate agents, but has changed their role from keeper of the listings to negotiator and guide.

Katie Curnette, director of communications at Zillow, recently searched for a home in the Seattle area. Her agent told her: "I'm not going to find you the house ... I'm going to get it for you. We'd find a listing, and he'd take us there that night," she says.

Some services, such as realtor.com and Redfin, are tied to the multiple listing service, and in many areas, you can search the MLS using agents' or company sites. How well this interface works varies by company, and you may want to experiment with several to find a search that fits your needs.

The services that are tied to the MLS are updated every 15 minutes, which makes those listings the most current. Listings on sites such as Zillow and Trulia can lag behind by hours or days. However, those portals have information that is not included in the MLS listings.

For example, a listing that has no address in the MLS-linked services may have an address at Zillow or Trulia. Most of the portals pull from public records data, which means the information is better in states where better data is available.

Both Trulia and Zillow sell ads to real estate agents, and the agents who advertise are highlighted next to home listings. The recommended agents are not necessarily the listing agents for the homes you see and may not even specialize in the neighborhood. So while you can email questions to those agents, you're usually better off finding your own agent through referrals and directing all questions and requests for showings to the agent working with you.

All the sites allow you to set alerts that notify you when a new property goes on the market. That's important in a competitive market, where you may need to jump on new listings immediately. Each service has its strengths and weaknesses. To turbocharge your home search, you will probably want to use more than one. Here is an overview of four of the largest online real estate services.

Redfin

Redfin set out to change the way people buy homes through technology. While its view of a totally electronic transaction has not come to pass, once you sign a contract, you can see all the documents related to your transaction online. "No rushing to Kinko's to fax late at night," says Jani Strand, a spokesperson for Redfin, which is a real estate brokerage and employs agents.

Unlike most real estate agents, who are independent contractors, Redfin agents are employees, and customer ratings help determine their compensation. In addition, Redfin rebates part of the commission to buyers. The company is currently active in 22 U.S. markets but does not work with buyers in the lower price ranges.

Because it is part of the MLS, the site doesn't disclose exact addresses if the seller prefers not to and does not display automated valuation data if the listing agent doesn't want it shown. In some cities it serves, Redfin provides a complete sales and listing history. Otherwise, you can usually find all that information on other websites.

[Read: What New Mortgage Rules Mean for Homebuyers.]

Redfin's listings come from the MLS, which means they are up to date. Its real-time alerts are often the first to arrive, usually within 15 minutes of a listing going into the MLS.

Redfin, like several of the services, uses an algorithm to show you homes you might be interested in based on your searches and the homes you have viewed. You also can search for homes by listing the school you want your kids to attend.

Zillow

Zillow rose to fame with its Zestimates, home value estimates derived from a proprietary formula that includes public records of home sales. As Zillow has gained more data, the estimates have gotten closer to reality, though they are still estimates.

Information from old listings lives on at Zillow, which can be valuable if a new listing doesn't include photos. It also has data on homes that are not for sale, and you can click on the properties near those you're looking at to see sales history, old listing data and other information.

Zillow has the most complete transaction history, which is helpful when you're trying to find out how long a home has really been on the market. It also includes data on homes that are in preforeclosure status and satellite maps that let you see what's near the homes you're looking at.

The service pulls data from a variety of sources, including public records, real estate agents, homeowners, tax assessors and some MLS services. Buyers and sellers can go online and update Zillow's data on their homes or list homes for sale or for rent.

However, listings sometimes live on as active after they have been sold, so it's wise to double-check the status of a home at one of the MLS-linked services.

Trulia

Trulia is also a portal that pulls data from a number of sources. It's a good place to start researching neighborhoods because it has a set of "heat maps" that let you easily see crime, schools, commute times and amenities such as banks and grocery stores in your target neighborhood. You can even look at the probability of a natural disaster, such as a hurricane or earthquake.

[See: A Step-by-Step Guide to Homebuying.]

"You can find some of these stats elsewhere, but you can't find it in this format," says Shannon Field, senior director of product management at Trulia.

In addition to searching for homes by ZIP code or city, you can draw a map of the area you'd like to search. Based on your search history, Trulia will send you suggested homes, as well as alerts on new listings or homes you have followed.

Realtor.com

Realtor.com is the listing site run by the National Association of Realtors. It's up to date, but it doesn't have as many added features as the other sites. Still, it's a good place to check to see whether a listing is current.