Peeking under the hood at Zillow

Zillow has $57 million in venture funding and a technology greenfield to create new online real estate features such as Make Me Move, a system that enables you to name a price so good you'll sell your home. Zillow's conundrum: How do you build technology infrastructure that can enable rapid product development and prepare for the long term?

The answer to that question falls to Zillow CTO David Beitel. Here's a look at what Zillow has under the hood.
--People: Beitel's first step in building Zillow's architecture was to build a team of techies. Beitel's requirements: Hire folks that have enough past experience to learn from mistakes. Zillow's development team hails from Amazon, Microsoft and Expedia among other places. "The main thing is to keep an open mind about technology and not get religious," says Beitel.
--Development: Zillow runs on hybrid Java and Linux on the front end and Microsoft SQL on the database layer. Beitel picked those platforms over Microsoft's .Net environment because he liked the flexibility. "It was close though and could have done it on Microsoft just as well," says Beitel. One persuading factor: Many of the top 100 sites also operate on Java and Linux.

"Overall I'm happy with the decision to use Java, there are a variety of frameworks and source code," says Beitel. "If you have a bug you can go in and fix it yourself."

The flexibility of Java and Linux has allowed Zillow to launch products quickly and the price is right (free) on Java frameworks such as Spring and Tapestry. Zillow's applications are mostly developed internally.

--Processes: Zillow has more than 80 IT employees, according to Beitel and many of them are new to the company. The key thing to do amid that rapid growth is to have strong testing methodologies for code each step of the way. "Testing is easy when you are small and there are 10 developers," says Beitel. "We had to plan early on to develop processes that can work five years down the road."  Zillow prefers to test code as it’s developed with a combination of home-grown tools and Winrunner from Mercury, now a part of Hewlett-Packard.

--Hardware: Zillow has outsourced its hosting and data center to AT&T. Storage, which is mostly provided by HP and NetApp, is a big challenge for Zillow since it has opened up its service to buyers, sellers and homeowners. All of these parties are continuously updating real estate information. This infrastructure is put to the test every time new services launch on Zillow.

Indeed, on Dec. 7 the Zillow site was down for hardware upgrades at 5:28 a.m. EST just ahead of the Make Me Move launch.

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--Networking: One area where Zillow's funding really helped out was in networking infrastructure. While every big purchase "is put through the ringer" regardless of the company's cash position, Beitel says being well funded enables a company to plan for long-term fixes. Zillow has built its networking infrastructure--featuring gear from Cisco, F5 and Force10, a high performance switch provider--to accommodate bandwidth requirements for the foreseeable future. "The funding makes us different from a lot of startups because we can plan longer term," says Beitel. "We should be able to scale nicely."

--Web 2.0, mashups et. al.: In a very Web 2.0 move, Zillow has opened up its API to others that want to use it. But when it comes to using other APIs Beitel says it pays to be more selective. "Accessing the software of others can give you quicker builds, but you have to read the fine print and pick and choose," says Beitel. "You have to make sure your partner will be around three years down the road and have contingencies in place."

Those contingencies include access to source code, which is a good to have if a partner goes belly-up. For an example of how Zillow picks and chooses see Beitel's response to my previous post on the company:

Our mapping systems are a bit if a hybrid. Using some 3rd party geocoding, street rendering and aerial photography, we have built our own mapping service. Additionally, we use Microsoft's Virtual Earth platform for our bird's eye views, which is super cool. Real Estate is the perfect application for this technology. We serve these maps and our own information, like parcels, housing information and Zestimates, through a flash based module. This allows us to make a dynamic and interactive user experience that is very hard to do in DHTML and browser based scripting.

--ROI: For Zillow return on investment is measured in faster time to market not necessarily cost savings. Zillow's game: Grow as quickly as possible. Beitel realizes that if Zillow keeps growing to the point where it would have to install an ERP system ROI will become a bigger issue. But for now Zillow is small and nimble and the company's ERP system consists of a few Excel spreadsheets and a Wiki or two.