Meanwhile, Zillow seems to be known as the premier site for real estate agents. It lists approximately 110 million homes, and is partnered with Yahoo! Homes, which generates additional exposure. Cynthia Nowak, senior PR manager for Zillow, says the company does extensive Google Analytics tracking, and according to that research, 61.3 million unique users visited Zillow’s mobile applications and websites in July 2013, representing year-over-year growth of 66 percent. In addition, 60 percent of Zillow’s visits now come from a mobile device (and on weekends it’s nearly 70 percent), and in July, 321 million homes were viewed on Zillow Mobile – that’s 120 homes per second. Zillow has also grown the most and the quickest, according to Experian and Inman News: Zillow has more than twice the number of realtor.com users on desktop computers, more than twice the number of Trulia users on mobile, and four times the size of realtor.com’s mobile users.

Zillow offers three tiered packages: Premier Silver ($10 per month), Premier Gold ($49 per month) and Premier Platinum, the price of which varies by ZIP code. All three packages offer “priority support” and a contact management widget, and they allow subscribers to create a customized website that features the agent’s MLS listings and is accessible by mobile devices. The Premier Gold package offers the same tools, but allows subscribed agents to appear at the top of search results. The Premier Platinum package allows agents themselves to be highlighted when buyers are searching a given area, and it displays the agent as a person to contact.

While each site makes lofty claims to attract a very high number of potential homebuyers, Zillow leads the way in overall traffic, with Trulia a close second and realtor.com a distant third.

Among the agents interviewed for this story, most agreed that they attracted the most attention for their listings, concrete leads and successful closings when using the Zillow platform.

RE/MAX agent Dawn Dause began using Zillow more than one year ago. She currently pays about $340 monthly to Zillow, which generates an estimated 15 leads per month and has given her the opportunity to close about 25 deals through the leads she gets from the site. Overall, Dause has been very pleased with the value provided by the platform.

“Zillow is very user-friendly,” she says. “I get very good qualified leads … I think that Zillow provides a much more positive website for the consumers and for the agents.”

Dause views Zillow as a much better lead-generating website than realtor.com or Trulia, but her satisfaction extends to the testimonials she has received after doing business on the site.

“I have over 20 reviews on Zillow, and I will get emails that introduce people to me and say that they are coming to me based on the strong testimonials online,” she says. “Realtor.com doesn’t provide this feature like Zillow does.”

These testimonials update directly to the agent’s badge, which allows her to stand out more to consumers.

Dollinger believes that Zillow has separated itself from the pack by offering a more open-ended platform, especially when it comes to contacting and working with the leads generated by the site. It is more open in allowing agents to use their own CRMs or auto-respond systems that are already in place, and the number of tools provided for lead generation is impressive, as well.

“[Zillow’s] tools are focused on helping agents grow their brand, and it has become a larger product provider than Trulia,” he says.

Dina Skinner, agent and owner of Meritage Realty Group, spends $331 per month on Trulia, but spends far more on Zillow, which she uses primarily. By her estimate, upwards of 50 percent of her sales (approximately $20 million in the last year alone) are derived from leads generated by the platform. As a former realtor.com user, Skinner has largely re-allocated her marketing dollars to Zillow.

However, she believes that the platform does have its drawbacks. Skinner often receives calls regarding properties for which she is not the agent, yet Zillow displays her picture next to the property description.

“I often get calls from buyers asking me for information about my listing, when it’s not my listing,” she says. “Can I get them information about the listing? Absolutely. I always get them as a client, but I feel like I am misleading them at the beginning. They are calling under the assumption that it is your listing.”

A report from Inman News published in 2012, cited in the article “Redfin Study Knocks Zillow/Trulia Listings Accuracy,” seems to support Skinner’s complaints. According to the report, 36 percent of Zillow properties and 37 percent of Trulia properties marked as “active” were no longer for sale in the local MLS. Also, the median number of days elapsed between the list date and the date on which the listing arrived at Trulia and Zillow was nine and seven days, respectively. While local MLSs feed into the larger portal sites, it appears that there is a sizeable holdup in information relay times, which can be frustrating for buyers and agents alike.