CoStar Streamlines Authentication and Increases Application Availability with F5 Solution

CoStar Group, Inc. logo


Improves efficiency with SSO

Delivers highly available applications

Decreases response time with web compression

Boosts flexibility with powerful iRules


Ease difficult authentication procedures

Make customer-facing apps available 24/7

Improve user experience

Customize traffic and applications

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As a commercial real estate information company, the CoStar Group, Inc. needed a simple and powerful authentication solution for its employees. By utilizing F5 technology, the enterprise implemented single sign-on, and also ensured the availability of their customer-facing applications while improving user experience across the board.

Business Challenges

Commercial real estate information enterprise CoStar maintains a large database of property specifications, photos, foot-traffic statistics, comparable sales and leases, and details about previous leases. Their customers include commercial brokers, investment bankers, large corporations, and individuals interested in the commercial real estate market. The company canvasses the U.S. and UK, visiting more than 500,000 properties annually and taking more than one million photographs.

All of this information has to be cataloged and then made available to CoStar’s customers, and with 10,000 calls to brokers and developers and 5.1 million changes in data every day, that’s a big task. “When we first bought the F5s nearly 20 years ago,” says CoStar Lead Network Engineer Ian Stong, “it was mainly for our external, customer-facing applications.” But over the years, the organization has expanded its use of F5 technology, relying on F5 BIG-IP Local Traffic Manager (LTM) and BIG-IP DNS to help manage the traffic flowing between their data centers as well as to and from their internal and external applications.

However, CoStar had other challenges it needed to address. With numerous applications accessed by internal users every day, the company’s time-consuming authentication process was beginning to impact the productivity of its employees. CoStar needed an authentication solution that would allow its users to enjoy the benefits and efficiencies of single sign-on without compromising the security that was so vital to the enterprise.

In addition, the company wanted to improve other aspects of the user experience, including boosting the performance of their internal and external applications.

BIG-IP APM is absolutely critical for a lot of our internal apps as well as some of the applications we have hosted in the cloud like Salesforce and Workday.


Having had a long relationship with F5, Stong knew that CoStar could use BIG-IP Access Policy Manager (APM) to control access to its internal network and streamline single sign-on (SSO) procedures across its network.

“We asked for some help from F5 with the BIG-IP APM deployment,” says Stong, “and everything works really well. BIG-IP APM is absolutely critical for a lot of our internal apps as well as some of the applications we have hosted in the cloud like Salesforce and Workday.”

CoStar used the BIG-IP devices they already owned to set up a test and development environment, which makes deploying new services and applications much simpler. “It’s easy,” says Stong. “Since we have the BIG-IP LTMs that we use for dev and test, it gives us the opportunity to flush some of the bugs ahead of time before trying to implement anything in our production environment.”

In addition, Stong makes use of some of the other features of BIG-IP LTM—including web compression and SSL offloading—to improve the user experience for both internal employees and customers. Finally, the organization employs the highly customizable F5 iRules scripting language to route internal and external traffic, adapt their applications to their specific business environment, and evolve the capabilities of applications and remediate any issues on the fly.

We also use F5 DevCentral, which is a great resource for iRules that people have already written.


CoStar deployed an F5 solution that allowed the enterprise to simplify and consolidate authentication procedures for employees, as well improve the performance and availability of its internal and external applications.

Boosts efficiency with centralized authentication    

CoStar has centralized its authentication process and implemented an SSO strategy for its many internal users. “We have a bunch of internal and external applications in the cloud that previously employees would have to log in to each one, so over the course of a given day, they might log into five or six different applications individually,” says Stong.

By deploying a solution with BIG-IP APM, Stong says that the once time-consuming authentication process has become much smoother. “The way we have it set up now, it’s basically SSO, so once you log in to the main portal, you’re able to click on half a dozen applications inside the cloud and you don’t have to authenticate again. People love it.” Currently, CoStar has deployed the solution for its employees only, but Stong says that based on the success they’ve had, the company is considering expanding it to CoStar’s customers as well in the future. 

Ensures application availability 

CoStar’s customer-facing applications are the lifeblood of the company’s business. By deploying high-availability pairs of BIG-IP LTM devices in its data centers, CoStar has been able to ensure that its applications remain accessible to its customers. “The BIG-IP LTMs give us all the benefits of load balancing combined with monitoring capabilities that allow us to check the backend of the app servers or database servers,” says Stong.

Being able to balance the company’s traffic and monitor the health of its network has made it easier to provide a reliable, robust services to CoStar customers. “It’s easy to bring a server offline if it’s having issues or having trouble responding to a specific SQL query,” says Stong. “It’s a real benefit. We’re able to mask issues with any internal resource better because we have that load balancing in conjunction with the monitoring.”

Increases performance

In the commercial real estate business, sometimes seconds count, and so Stong says he uses BIG-IP LTM to boost performance. “We offload resources from the web servers and improve the experience for our customers by doing web compression to decrease the response time of our applications.”

Stong says that CoStar also realizes load balancing and reverse proxy benefits for internal applications, “like Citrix VDI, Outlook, and some custom apps.” Using real-time protocol and traffic management decisions based on application and server conditions, BIG-IP LTM helps the CoStar team optimize their network infrastructure to increase employee productivity. 

Customizes application delivery

CoStar relies upon the flexible iRules scripting language to adapt applications to new uses, mitigate some vulnerabilities, and customize application traffic handling. In addition, Stong says that iRules help CoStar keep things running smoothly in their data centers. “The developers say, ‘We need this capability,’ and we’ll develop and implement the iRule,” says Stong.

“And we also use F5 DevCentral, which is a great resource for iRules that people have already written.” The IT team has been able to adapt some of those already written iRules to use for their own environment. “It really comes in handy,” Stong says. “There’s no need to reinvent the wheel.”