Realie vs. ATTOM: Comparing Property Data APIs for Developers

ATTOM has been a major name in U.S. property data for years, with a broad offering across assessor, recorder, mortgage, foreclosure, valuation, and other real estate datasets.

Realie was built around a different model: self-service access, direct collection from public property-data sources, modern developer tooling, and infrastructure designed for low-latency API use.

One of the clearest differences between the two platforms is API performance, so we tested both using the same 100-property test set across 25 states.

Realie vs. ATTOM API latency

For the ATTOM benchmark, we tested the /property/basicprofile endpoint across 100 unique properties in 25 states. Each property was queried once, the request order was randomized, a persistent HTTP session was used, and connection warm-up requests were excluded from the results.

ATTOM successfully returned a property for all 100 of 100 requests, giving us a clean benchmark without failed or empty responses affecting the results.

We then ran the same 100-property test set through Realie.

In this benchmark, Realie's mean response time was approximately 76.5% lower than ATTOM's, while Realie's P90 latency was approximately 76.8% lower.

Another way to look at it: ATTOM's measured average response time was about 4.3× Realie's during the test.

For developers building property data directly into search, underwriting, valuation, lead generation, or other user-facing workflows, that difference can be meaningful. Faster response times can reduce loading delays and lessen the need for additional caching or background processing to keep an application responsive.

These results represent our observed performance from a September 2026 benchmark. API latency can vary based on network conditions, infrastructure load, query type, geography, and other factors.

Realie's address lookup documentation covers the endpoint used for low-latency property lookups.

We also tested several other ATTOM endpoints

The broader ATTOM test included several additional endpoints using the same Denver property, with 20 measured requests per endpoint.

Average latency varied by endpoint:

• Assessment Detail: 131.8 ms

• Sales History Snapshot: 143.4 ms

• Sales Detail: 196.6 ms

• AVM Snapshot: 186.1 ms

The larger differences appeared in tail latency. During those tests, Sales Detail reached 579.6 ms on its slowest request, while AVM Snapshot reached 957.2 ms.

Because those endpoint tests used only 20 measured requests each, they are best treated as directional rather than as definitive P95 or P99 performance measurements. What they do show is that response times can vary meaningfully across ATTOM's different property-data endpoints.

Developer experience: two different approaches

Performance is only one part of integrating a property-data API.

ATTOM's documentation is extensive and reflects a more traditional enterprise documentation model. Information is spread across the Developer Platform, API reference, guides, data dictionaries, and ATTOM Cloud help content. ATTOM also provides interactive documentation and code examples.

The main difference is organization and workflow. Compared with newer developer platforms, some information can take more navigation to locate, and the overall experience is geared more toward established enterprise users than rapid, self-service implementation.

Realie has taken a more modern, developer-first approach. Endpoint pages put request parameters and examples directly alongside the API reference, the documentation includes an llms.txt index for AI development tools, and Realie provides both a CLI and code-reference resources for common integration tasks.

For teams building with Cursor, Claude Code, ChatGPT, VS Code, and other AI-assisted development environments, that kind of structure can make integration faster and easier to navigate.

Pricing and contract structure

The commercial model is another substantial difference.

In a March 17, 2026 email from ATTOM Data Solutions that we received, ATTOM described its API as an annual contract and provided the following monthly pricing:

For context, the pricing above reflects the rates ATTOM quoted in that March 2026 email and may not represent the pricing every customer receives today. ATTOM also notes on its developer site that pricing can vary based on usage and customer needs, with higher-volume requirements typically handled through enterprise plans.

Realie takes a more self-service approach. Pricing is published publicly, plans are month-to-month, and standard API access does not require an annual commitment. See Realie's pricing.

That difference can matter most for startups and smaller teams. A company with a predictable, established data workload may be comfortable with an annual enterprise agreement, while an earlier-stage company may prefer the flexibility to start at a lower monthly tier, validate a use case, and scale usage over time without committing to a long-term contract.

Both models can make sense depending on the buyer. The main difference is that ATTOM is structured more like a traditional enterprise data provider, while Realie is designed to make it easier to start small and scale as usage grows.

Where does the underlying property data come from?

ATTOM describes its database as multi-sourced, combining public records with proprietary and third-party data. ATTOM discusses its sourcing approach here.

Realie takes a more direct-source approach. We collect and normalize property data from county assessor, recorder, and other public-record systems, and where counties require paid access or data agreements, we work directly with those sources. Read more about Realie's data platform.

That difference matters operationally. When we find a problem with a field, county format, or source record, our team can trace it back to the underlying source and update the ingestion logic directly.

No property dataset is perfect, and county records themselves can be inconsistent or delayed. But Realie is designed to keep the path between the original public record and the API as direct as possible.

So which model makes sense?

ATTOM is built as a traditional enterprise property-data platform, with broad datasets, specialized products, and multiple delivery options.

Realie is built for teams that want to get started quickly. Developers can create an account, get an API key, test the data, and scale usage without beginning with a large annual contract.

Performance is part of that difference. In our September 2026 benchmark using the same 100-property test set, ATTOM's Basic Profile endpoint averaged 232.6 ms, while Realie averaged 54.6 ms.

Realie is built around fast API response times, self-service pricing, modern developer tooling, and direct-source data collection. For teams that value those things, that is the experience Realie is designed to provide.