What Technologies Should You Use for Building a Real Estate Platform in 2021?

In one of our previous articles, we talked about the current state of the online real estate market and developing a Zillow-like real estate marketplace. Yalantis is a technical partner of Zillow, the top global real estate platform. We also have experience developing European real estate marketplaces. 

Our American and European clients usually come to us inspired by the market success of Zillow, Redfin, and Realtor.com. In this tech stack guide to developing a real estate platform, we’ll analyze this trio in terms of the fundamental aspect of any real estate platform: property listings. They’re key to success, as a low quality of listing data, a lack of data, or duplicate listings will inevitably turn off users. 

In addition to the real estate tech stack needed for ensuring a quality real-time data flow, we’ll discuss how the experience of top American property marketplaces is applicable to the European market. For maximum benefit, we’ll also give you tips on how to build scalable and flexible real estate software that you can easily improve and modernize. 

Let’s dive into real estate app development and find out where leading platforms take data from.

What’s the difference between Zillow, Realtor.com, and Redfin?

From the great variety of real estate platforms on the market, Zillow, Redfin, and Realtor.com are the traffic leaders and considered as best solutions for finding and selling properties. 

According to Statista, Zillow is the leading real estate app in the US, with 36 million visits a month as of January 2020. Trulia, owned by Zillow, is the second most popular real estate website, with 23 million monthly visits. Yahoo! Homes, with 20 million visitors, and Realtor.com, with 18 million visitors, are next on the list. Redfin closes the top five with 6 million visitors.

zillow real estate marketplace

Business models

Originally, Zillow mainly got revenue from charging agents an advertising fee while providing free services for homebuyers. In 2018, the company launched the Zillow Offers program through which Zillow purchases properties itself and sells them to other platform users. After launching Zillow Offers in April 2018 in the Arizona region, home sales revenue outpaced Zillow’s revenue from traditional sources in the third quarter of 2019.

Realtor.com gets revenue from providing agents with software tools, including referral-based solutions like ReadyConnect Concierge and lead generation solutions like ConnectionsSM Plus. The company also offers several advertisement options for agents, brokers, lenders, and consumer media.

Unlike Zillow and Realtor.com, Redfin is an actual brokerage that pays its real estate agents a base salary and makes money when users buy or sell homes through its agents. The company earns commission from selling properties as well as from seller listing fees that depend on the location. For instance, in Atlanta, the fee could be 1.5 percent, while in Denver it could be 1 percent.

Read also:How to Build a Real Estate Web Platform [Core Features and Add-Ons]

Relevance of data

Listings on Realtor.com and Redfin are supposed to be accurate and up to date because these websites are directly linked to multiple listing services (MLSs) — databases created by cooperating real estate brokers to share data about real estate for sale. Real estate listed on an MLS appears on Redfin and Realtor.com as soon as it’s listed by a broker. 

Realtor.com claims that more than 90 percent of their for sale listings are updated at least every 15 minutes. The company works closely with MLSs to decrease update times.

According to Redfin, most of their listings are refreshed every five minutes. It may take 48 hours for a for sale by owner (FSBO) listing to appear on Redfin, however, since the company carefully checks listings published by owners.

Zillow claims that it takes from 24 to 48 hours for MLS listings to appear on the site. FSBO listings must be posted manually on Zillow through a homeowner’s profile. Every FSBO listing goes through a verification process, so it takes up to 72 hours for them to appear on the website.

Later, we’ll pay attention to how your real estate platform can ensure the relevance of property listing data.

the realtor.com app

Where can a real estate platform get data for property listings?

There are three ways of ensuring a flow of real estate listing data to a real estate platform. The first is mainly applicable to the US market, while the others are applicable to any market. 

1. Pulling data from MLSs

In the US, MLSs are common and are technologically supported by the National Association of REALTORS® (NAR), which ensures interoperability of data between MLS systems. As of 2020, there were 597 MLSs in the US. Brokers participating in an MLS agree to share their listings with other MLS participants. 

MLSs usually send data to their participants and technology partners through the RESO Web API standard. MLSs allow real estate portals like Zillow, Redfin, and Realtor.com to publish MLS listings on their websites. 

Unlike in the US and Canada, MLS property technology is poorly developed in other countries. There are some forms of MLSs in European countries including Germany, Spain, Italy, and the United Kingdom. However, these countries still lack regulations regarding real estate transactions. Consequently, differences in software packages across real estate agencies make it challenging to share data.

the redfin app

How can your platform pull data from an MLS?

MLSs share their data with participating brokers or software technology partners through their own web APIs. Trulia and Zillow get access to local MLSs by negotiating data sharing and syndication agreements. Redfin, on the other hand, doesn’t have any of that headache. As a brokerage, it’s free to use data available through its membership in the Realtors MLS.

In this regard, it seems like Zillow is doing things the hard way. After all, it could become a brokerage and pull data directly from an MLS. However, becoming a brokerage imposes a lot of legal obligations on a company because they then need to participate in sales by representing buyers and sellers within their MLS, which basically means they have to employ agents and manage them across the whole country.

  • Internet Data Exchange

It’s important to note that in the US, public property details should comply with certain rules established by the NAR and must follow the IDX (Internet Data Exchange) policy. To enable data exchange between an MLS database and your website, you need to integrate IDX. 

IDX is a set of standards, rules, and technologies that track real estate data as it moves from an MLS to your platform. IDX moderates how your platform accesses MLS data and how it’s publicly displayed.

  • Methods of receiving MLS data

Depending on the MLS you need to take data from, your platform can get listings by means of different methods including iFrame, FTP, and RETS. 

The most modern method is the RESO Web API. Agents and MLSs are increasingly adopting this standard. It streamlines the movement of listings and can significantly cut local hosting and security costs. Paired with the RESO Data Dictionary, the RESO Web API standardizes the structure of property listings.

There are also third-party services that provide APIs that normalize data flows from MLSs. You can check out SimplyRets, ATTOM Property API, and Mashvisor API. 

What is the simplest way to connect with multiple MLSs?

Because there are hundreds of MLSs all over the US, it’s extremely burdensome to negotiate agreements with all of them, especially if you operate nationwide. That’s why the largest aggregator websites enter into data sharing agreements with national real estate companies to get their data directly from MLSs.

These companies include 365 Connect (a provider of technology for the housing industry), the RealBird social media and mobile listing marketing platform, and JBGoodwin REALTORS®. ListHub is one of the largest aggregators of real estate listing data in the US and used to be the main source of listings on Zillow and Trulia until their agreement ended in 2015. Now, ListHub collects and distributes real estate data from Realtor.com, Zillow, and other real estate websites.

You would need to do three things to get access to these platforms: get licensed in every state, join each MLS you need to access, and integrate data that doesn’t follow a consistent standard across the 900+ MLSs.

2. Encouraging agents, brokers, and landlords to publish properties

Zillow is doing fine attracting real estate agents and brokers to their website. The main way the company attracts landlords is by providing them with a convenient tool to manage all their listings in one place. Encouraging real estate professionals to share properties with your platform also has much to do with how you help them promote their services.

When building real estate platforms, we often implement optimized media services, ensuring a platform is capable of simultaneously uploading up to 50 images each up to 20 MB in size for any real estate listing. Such top-notch technical capabilities help agents present properties to potential buyers in detail. To optimize your media service, you can use tools like AWS Lambda.

The list of benefits your platform might provide to real estate workers is mindblowing and requires marketing research. Each successful real estate website uses their own hooks. Rightmove, the top real estate platform in the UK, provides agents with exclusive member benefits like marketing and communication tools, reports, and a telephone lead service so they don’t miss leads’ requests. 

redfin has a convenient draw your own search feature

3. Encouraging homeowners to publish properties

Zillow also allows FSBO listings, enabling homeowners to list their own homes without the assistance of professional agents. Homeowners can post listings directly on the platform after registering. Listings are verified, and if they don’t violate Zillow’s rules, they’re posted on the platform.

Redfin takes information on for-sale-by-owner listings from Fizber.com and FSBO.com and doesn’t allow users to post FSBO listings directly on their website. But Redfin’s primary data source is MLSs, so in case someone is trying to post a listing on an MLS and as an FSBO, the website will display only the MLS listing. Realtor.com is sceptical about FSBO listings, so it doesn’t allow homeowners to post them on the platform. 

What’s interesting, however, is that properties on Zillow don’t necessarily have a “for sale” label. The owner of a property can state the price they'd be willing to sell their home for without actually putting it on the market. This type of listing is called Make Me Move. It’s a great way to measure interest from potential buyers and even get an unexpected offer. FSBO is potentially a great opportunity for emerging real estate businesses in the US and Europe.

fsbo listings on zillow

Keep in mind that consumers are annoyed with seeing dozens of listings for the same property on real estate platforms. Try to avoid duplication of properties on your platform.

To ensure the uniqueness of listings on real estate platforms we build, we implement a moderation flow. When being published, all properties go through an automated check based on the property address. If the property is suspected of duplication, we pass it to the admin panel for a manual check. Additionally, you should allow agents to claim ownership of a property if they notice other agents offering it too. 

What data other than property listings does a real estate app need?

Other than information about properties, a real estate website generally has data about neighborhoods, schools, points of interest, demographics, past sales, and other things that improve the home buying and selling experience.

Zillow provides APIs with neighborhood information for their listings and a dataset that contains neighborhood boundaries. Here are other important APIs for system integrations to retrieve geographical and neighborhood information:

  • GeoNames has a comprehensive dataset of over 25 million geographical names.
  • The Google Places API gives you information about nearby places such as cafes, cinemas, and sports clubs. 
  • Mapbox allows you to build custom maps for real estate listings. For more on this service, read our article on Mapbox versus Google Maps.
  • Almost all cities in the US have open data portals with a variety of information you can use in your app. Many European cities including Dublin, Florence, Ghent, Helsinki, and Lisbon also have portals in place.


An important step in real estate platform development is using modern technologies that will empower your property listings and ensure your platform is scalable to handle a growing number of users.

  • Create a modern microservices architecture built on the principles of security, scalability, modularity, and ease of functional expansion. 
  • Provide quick, flexible, and smooth search and filtering by any number of criteria using tools like Elasticsearch.
  • Over seven in ten agents have found photos, videos, and virtual tours more valuable since the start of the COVID-19 pandemic compared to before the pandemic according to a recent NAR survey. You can implement must-have 3D tour functionality on your platform using third-party services like EyeSpy360.


Digital transformation marks a drastic rethinking of how businesses use technology. The real estate industry, like lots of other industries, is making its way into the cloud. You can learn how to move your system to the cloud-based infrastructure in one of our articles

Developing real estate custom mobile solutions and web apps is challenging. But now you know what makes it possible for huge companies like Zillow, Redfin, and Realtor.com to pull real estate data into their apps and websites. 

Yalantis has extensive experience building real estate platforms and property management software based on prior competitor research, principles of modern microservice architectures, and sophisticated functionality. Contact us if you’re ready to discuss your software solution.  

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