Cluster Buck Rogers!

Big news! Redfin has begun clustering listing search results! We’ve rolled out the feature to Seattle, Portland, the Bay Area, Sacramento and Phoenix so far, and expect to offer it across the site by this Friday.

Clustering fixes a big problem. For years, the result most visitors have seen when first searching the site has been an error message that prompted users to zoom in:

Visitors’ most common reaction to this warning was to leave. And many did just that. The problem is that first-timers often start by searching broadly, on cities like Seattle or Boston that contain thousands of listings, which are difficult to display on a single map.

Most sites create multiple pages of results, forcing the user to flip through pages for listings that in reality may be separated by only a few feet of lawn.

But we prefer to think of Redfin as an application, not a book, where the map shows the entire lay of listings across the land. If we can’t create a work-space that shows all the listings for an area, we don’t show any listings at all.

With today’s upgrade, we still ask users to zoom in on a workable number of properties, but clusters guide that process, creating targets on the map for users to click, sized according to the approximate number of listings in that area:

Redfin dynamically sizes and locates the clusters based on a real-time survey of listings in the area. As a result, we never show an out-of-date view of the listings in an area. To calculate the size of very large clusters quickly, we do however round to the nearest multiple of ten or five.

My God, It’s Full of Stars!
What you’ll notice first when you click on a cluster from a Safari or Chrome browser is that the cluster explodes into more clusters, or a scattering of homes, that slide and re-size across the screen. This looks cool. And we coded it in a cool way, using CSS Transitions, a technology associated with the new language of the web, HTML5.

When you mouse over a cluster, you see the shape of the cluster, the number of houses and condos within the cluster, and their price range. This mouse-over display uses CSS Transforms, also associated with HTML5.

What delicious eye-candy! But it serves a larger purpose, to animate the whole work-space so that it can stream more information to our users. As Redfin engineering vice president Sasha Aickin notes, a 30-second video conveys more information than a picture you stare at for 30 seconds.

We think animation can have a similar effect in a real estate application. So now that we’ve committed to emerging web standards, you’ll see plenty more dynamic features added to Redfin, highlight listing photos and charting pricing trends. The experience, we hope, will blow you away.

(Almost) No Browser Left Behind
But what about the rest of the browsers? Firefox 4.0, now in beta, also supports these animations. And except for Internet Explorer 6.0, all the other browsers still show clusters, but without the mouse-over or animation effects. We worked hard to recognize which browser you prefer, and to support that choice.

We’ve still got more big changes to the website coming this week, but we’re rolling them out bit by bit to make sure the site doesn’t crash.

For now, many thanks to the designers and developers of clusters, Navtej Sadhal, Darren Yeung, Michael Smedberg, Ben Fulton, Dan Fabulich, Andy Taylor and Jane Nemenman, all of whom, undoubtedly, are anxious to hear what you think…


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  • alexlod

    Guys, this is seriously awesome. Well done!

  • Marce

    Yep, this area/neighborhood supernova effect is pretty darn fun, and functional too. A definite home run, everyone!

  • Justin Martin

    No IE9 Beta support for animations? Great idea and implementation though.

    • Sasha Aickin

      Justin: Thanks! Unfortunately, IE9 doesn't support CSS Transitions, which are what we used to do the animations on Safari/Chrome/FF4. Microsoft has put a lot of work into the performance of their animation engine for IE9, but as far as I can tell it's only the <canvas> tag. While we'd love to get animations on IE, re-implementing the map layer in canvas just isn't practical.</canvas>

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  • Tom


  • Sasha Aickin

    FYI, we launched clustering for the Bay Area, Sacramento and the Central Valley, and Phoenix this morning. More markets to come!

  • Ken Geis

    That's awesome. Can I recommend that you present average price in whatever base appropriate? It was unnatural for me to see that the average home price in El Cerrito was $0.53M. $530K would be better.

    • Sasha Aickin

      Yowch, you're right. We're rounding incorrectly: above 500K gives $0.xxxM and below gives $xxxK. Silly bug, and I apologize. I'll add it to the bug DB.

  • Nik Nak

    Okay, I seem to be the only person with a gripe, but I HATE the new format!! These “awesome” clusters, at least in Portland, make it very difficult to view the scattering of houses in a neighborhood. By the time you zoom in to get past the cluster icon and see the house icons, the map is just a few blocks wide and greatly reduces your capacity to browse. Is there anyway that we old time Redfin fans can opt out of this new feature? Seriously, why can't the internet be a little bit like the NYTimes and stop messing with the format when it works??!!

    • Andy Taylor

      Hello Nik – Clusters will actually only ever display in situations that you otherwise would not have seen any homes at all (instead, seeing the over “X” limit error that Glenn describes). So in this regard, we're actually not removing any functionality at all, just trying to give you a better experience instead of that annoying error message).

    • Sasha Aickin

      Nik, Sorry you're not enjoying clusters. Andy's right, though, clusters don't appear if we can show you homes. The real problem here is that Portland's MLS is very restrictive with how many homes we can show at once; they only allow us to show 100 homes on the map at once, so we have to show clusters at much lower zoom levels than we do in other markets. The limit for Portland used to be 200, but it was recently lowered to 100 when we pulled in recent sales information.

      If you add some search filters (beds, baths, price, etc), you'll filter out some of the homes you don't want, and therefore you'll be much more likely to get homes rather than clusters at higher zoom levels. And for our part, we try and push for higher limits in Portland; we know it's a problem for our user interface.

      • Nik Nak

        Thanks for taking time to respond, and thanks for the tip about filtering info. Will do!

  • Steve Crossland

    Pretty cool. I've seen this in other mapping applications and wondered why it's not more widely used in real estate searches.

  • Crystal Beasley

    Maybe it's just for Portland map, but I'm no fan either. Once you're zoomed in past zoom level 5 the clustering snaps back into place. It's super annoying. Sorry guys. I'm sure it makes it faster to render the map, but it's ultimately making it a much more frustrating experience for me to pan around. I'm more than happy to wait an additional few microseconds to get a view that useful.

    A little background on the way I use maps… I have a very specific area that I'm looking for homes. Being at zoom level 5 gives me the whole area I'm looking at, all of 97214. Zooming in one more click is just too close in and I loose my landmarks, but that's the threshold where clusters seem to go away. If you just backed it out just one zoom level I'd be perfectly happy.

    Somewhat of a compromise would be to make clicking on the cluster expand that cluster but NOT zoom you in.

    I'd love to be a beta tester for your ux. I'm @skinny on twitter. Love your site. Love what you do.

    • Sasha Aickin

      Hey Crystal, thanks for the feedback. As I said above to Nik, the problem is that in Portland we're not allowed to show more than 100 listings on the map at once. We would *love* to expand the clusters at the zoom level you want, but the Portland MLS won't let us. If you look in Seattle or San Francisco, you'll see that you get out of clusters much sooner as you zoom in.

      It's an interesting idea to expand a single cluster (while leaving the other clusters on the map unexpanded) and not zoom in. I'm worried that it would be very confusing for users, as they may not understand why homes appear in one part of the map but clusters in another. I'll play with it, though, and see if we can make it work.

      It's also worth noting that the clusters are not tied to the zoom level; they are tied to how many listings come back. If you do a search that returns fewer than 100 listings, no matter the zoom level, we will show you the homes, not the clusters. As an example, here's a search for 97214 restricted to $150K-$650K and excluding multi-family: . It comes in with 96 homes right now, which means it's not clustered. I know it's a pain when you want to just see all the homes, and we'll continue to push the Portland MLS to let us display more at once.

      As for UX testing, thanks for the offer. We generally like to do user testing in person, but we'll keep you in mind.

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  • Ralpht

    When i first read the title, i was thinking, “that's awesome, redfin is providing data about where puget sounders are actually searching for homes”. I was expecting a Seattle Times like report on where the most activity is and some insight about what people are really looking for, as it would help to identify, even in a flat/down market, what/where people value the most. Now THAT would have been cool.

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  • White Bear Lake Homes

    Nice work on these clusters, Redfin. You have caught the attention of AgentGenius on this new technology roll out, and I have nothing but respect for you guys that are constantly pushing to advance the real estate technology landscape. Aweomse!

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  • Phone8007062055

    Navtej Sadhal, Darren Yeung, Michael Smedberg, Ben Fulton, Dan Fabulich, Andy Taylor and Jane Nemenman whenever and wherever you guys and gals code this stuff, Yummy! The new graphics/listing info scroolovers are awesome. Now help me find that fixer-upper house in Marin


    I'll try this again here. Any plans for an Android App?

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