Improving Application Reliability Using Amazon Keyspaces at Zillow

Launched in 2006, Zillow empowers buyers, sellers, renters, real estate professionals, and the residential real estate industry with information, products, and services to make moving easier. With 221 million monthly unique users across its apps and sites in 2024, about 165 million homes in its living database, and 1.9 million active rental listings, Zillow is making home a reality for more people.

Zillow’s users can save search criteria and receive notifications when relevant changes occur, such as a new listing, an open house date, or a price cut. The database that supports the Save Search feature is business critical, so Zillow wanted to migrate to a managed database solution that would provide enhanced reliability, simplified operations, and comprehensive technical support.

For 10 years, Zillow has used AWS services to power other areas of the business. The company looked to Amazon Keyspaces for a solution that was horizontally scalable, capable of handling its throughput, and compatible with its existing architecture, which was built on Cassandra query language.

“The ease of transition was important to us,” says Heidi Peer, senior manager of database engineering at Zillow. “We wanted a simple migration that didn’t require rewriting or architecting lines of code. Our business has other priorities and features to focus on.”

The migration didn’t require significant changes to the company’s schema or queries. Zillow took a methodical approach and worked closely with experts from AWS to implement a gradual migration. “AWS has really good documentation, and it was helpful to have experts from AWS to reach out to for technological support,” says Jason Cowan, senior software engineer at Zillow. The company fully transitioned to Amazon Keyspaces in August 2023. “We didn’t have any outages,” says Cowan. “The migration was extremely smooth.”

With a managed solution using Amazon Keyspaces, Zillow significantly reduced operational overhead. Ian Blackburn, a senior database engineer at Zillow, had previously led the team responsible for resolving technical issues related to this solution. Now, Blackburn and the rest of the Zillow team can rely directly on the support and assistance of the AWS team. This direct access to the AWS team has driven operational efficiencies at Zillow, leading to fewer technical issues and less need for frequent internal troubleshooting.

Using Amazon Keyspaces, Zillow also has access to point-in-time recovery instead of needing to make daily backups. “If I ever have to do a restore using Amazon Keyspaces, it’s really simple,” says Blackburn. “It’s not much more than a point-and-click procedure.”

Zillow achieves low latency and high performance using Amazon Keyspaces. The company can also scale to efficiently support varying traffic needs using the automatic scaling feature, which helps provision and adjust throughput capacity automatically for variable workloads. “After the migration, we are a lot less reliant on DevOps and more on self-service most of the time,” says Cowan.

By migrating its Save Search database to Amazon Keyspaces, Zillow increased reliability by reducing outages and enhancing monitoring capabilities. Using Amazon CloudWatch—a service for observing and monitoring resources and applications on AWS, on premises, and on other clouds—Zillow can investigate issues more reliably without requiring support from a database engineer. “Having standardized monitoring features on AWS is extremely beneficial,” says Cowan. “I can correlate errors quickly and simply using the dashboards that Amazon CloudWatch provides.” Instead of investing time in maintenance and troubleshooting, Zillow’s teams are freed up to focus on innovation.

“It was a no-brainer when we considered migrating the Save Search database to Amazon Keyspaces,” says Peer. “We needed a managed solution along with compatibility, ease of migration, and an ability to mitigate significant operational risks. The benefits of improved support, stability, and scalability make Amazon Keyspaces a great fit for our business.”