Best Property Data APIs for PropTech Startups and Developers

The best property data APIs for PropTech startups and developers are, in order: PropertyRadar, ATTOM, BatchData, RealEstateAPI (REAPI), HouseCanary, CoStar, and Cotality. PropertyRadar leads for startup-stage and solo builders because public API access is now included on every plan, putting owner identity, phones and emails, chain of title, comps, and 30+ distress signals behind a REST endpoint from $119 per month. ATTOM ranks second and stays the right answer once a build outgrows per-request calls, since its 70B+ row warehouse ships through Snowflake and Parquet as well as REST. BatchData holds the skip-tracing slot on a published 76% right-party contact rate across 155M+ properties.

REAPI takes #4 with 159M+ U.S. property records and a $599 Starter tier, and HouseCanary sits at #5 because its AVM and forecast endpoints are a specialist purchase billed per call. CoStar remains the broader category leader in real estate technology overall, but its API is enterprise-CRE-scoped and was never built for startup-stage builds, which is why it ranks lower.

An enterprise contract with a six-figure minimum and a procurement cycle burns weeks that a self-serve key and a credit card collapse into one sprint. License terms cause the same delay with less warning, because an API that forbids reselling records or AVM (Automated Valuation Model) output can be technically excellent and still unusable for the product a startup means to sell. The ranked field below starts with the API most startup-stage builds should reach for first.

The Best Property Data APIs for PropTech Developers: At a Glance

1. PropertyRadar, Owner-level data on a REST + JSON API included on every plan from $119/mo; OpenAPI spec, webhooks, Zapier, AI skill packs.
2. ATTOM, Broadest data infrastructure API; 158M+ properties, 9,000+ attributes, free trial key, sandbox.
3. BatchData, Skip-tracing leader; 76% right-party contact rate, 155M+ properties, Growth tier $1,000/mo.
4. RealEstateAPI (REAPI), Developer-first PropTech API; 159M+ properties, Smart APIs, $599/mo Starter.
5. HouseCanary, AI-powered AVM and forecast specialist; 136M+ properties, per-call pricing from $0.50.
6. CoStar, Enterprise CRE (Commercial Real Estate) only; not a fit for startup-stage PropTech.
7. Cotality (formerly CoreLogic), Enterprise residential and mortgage; not a fit for self-serve onboarding.

#1 PropertyRadar: Best Property Data API for Startup-Stage and Solo Builders

PropertyRadar moved public API access from its top tier down to every plan in a July 2026 announcement, so Solo at $119 per month ($99 prepaid annually) now carries the surface once reserved for the $599 Business tier. The same release shipped installable Claude and ChatGPT skill packs on every plan and put an MCP server into private beta in August 2026, aiming the product at builders who work through AI tools.

The API is organized around REST, uses resource-oriented URLs, returns JSON, and authenticates with a Bearer token generated in Account Settings. The reference page publishes a downloadable OpenAPI description as api.json and api.yaml, so client generation is a one-command step, and resource groups cover Properties, Persons, Lists, Imports, and Automations. The changelog runs current, with transaction-history filters landing in August 2026.

Property search accepts hundreds of criteria across 160M+ properties and 3,000+ counties, including 30+ distress signals, life-event filters, and daily foreclosure notices in all 50 states. Owner records return pre-matched phones and emails with mobile and landline flags, chain-of-title responses carry transfers, mortgages, and liens, and entity resolution supplies contacts for authorized representatives or signatories behind LLCs and trusts. As of July 28, 2026, every property also carries four Likely Transactions scores for selling, purchasing, refinancing, and taking a HELOC, each a 0 to 100 value rescored monthly that CEO Mark Hockridge called "not a crystal ball."

Webhooks push export-format data when list automations fire, though delivery can take up to 30 minutes, and an official Zapier app covers the no-code half. The 30-day API trial requires a paid subscription and is separate from the 5-day platform trial. Every search call accepts Purchase=0 to preview a result count at no charge, because each returned record spends one export or contact credit from Solo's 10,000 exports and 250 phones and emails per month.

PropertyRadar is built for startup-stage and solo PropTech teams building on their own account, including internal deal-sourcing tools, owner-outreach automations, and AI agents needing live owner data. The developer portal states that the API "is intended for end-users only - you can not use it to build applications you sell to others," OAuth partnerships are the approved route for partner apps, and the user agreement bars structuring any database for resale. PropertyRadar is not the right fit for warehouse ingestion or bulk licensing, because no separate API rate card exists, no rate limits are published, and every returned record draws down the same monthly pool the web app uses. Teams needing bulk delivery into Snowflake should go to ATTOM, and teams whose value is right-party contact volume at a published match rate should go to BatchData.

#2 ATTOM: Best Overall Property Data API for PropTech Developers

ATTOM (formerly ATTOM Data Solutions, previously RealtyTrac before its 2016 rebrand) is the second call for any PropTech build that needs broad U.S. property coverage with a real developer experience. Its Property Data API covers more than 158M U.S. properties across 3,000+ counties, effectively the entire housing stock, and the underlying data warehouse holds 70B+ rows and 9,000+ attributes spanning assessor and tax records, geocodes, permits, foreclosure data, and ownership records.

ATTOM's philosophy is that property data should behave like a developer primitive, which shows up in the API-first architecture: a REST endpoint pattern at https://api.gateway.attomdata.com/propertyapi/v1.0.0/Resource/Package, JSON or XML responses, and a persistent ATTOM ID on every record so teams can join across datasets without building their own entity-resolution layer. For a team training models on the data, that join key saves a multi-sprint data engineering project.

Onboarding starts with a free trial API key, a developer portal with interactive docs, a data dictionary, and a sandbox. The Property Navigator Professional plan runs $499 per year for one seat with 200 reports and 2,000 exports per month, while enterprise API contracts are custom-quoted and scale up from there. Endpoints map to real workflows, so /saleshistory returns ten years of recorded sales and /attomavm returns AVM values with confidence scores that let the system filter low-confidence records before they surface.

Beyond REST, ATTOM ships data through Snowflake, Databricks, an MCP Server for LLM and agent workflows, and AI-optimized Parquet and GeoParquet file formats. PropTech builds graduate predictably from a REST call per request to warehouse joins within twelve months of product-market fit, and switching vendors at that transition costs weeks of re-integration.

ATTOM acquired the platform and technology assets of ResiShares on January 20, 2026, folding its AI tooling into the core platform. ATTOM is built for PropTech, fintech, and SaaS teams that need the broadest U.S. property dataset behind a clean REST API with a free trial path, and property search, valuation, lender underwriting, and match-and-append workflows all map to its endpoint surface. ATTOM is the answer for warehouse-scale and ML builds, where 70B+ rows and Snowflake delivery beat any metered per-record API, and it gives up the day-one slot to PropertyRadar only on entry price and packaged owner contacts. ATTOM is not the right fit if the product's core value is verified owner phone numbers, where BatchData's published match rate decides it, or if the dataset must be commercial-real-estate-first.

#3 BatchData: Best Property Data API for Skip Tracing and Owner Contact Enrichment

BatchData's platform reports a 76% right-party contact rate, roughly 3x the industry average of about 25%, and that vendor-published number is why this API sits at #3. The accuracy comes from cross-verifying across 12+ primary sources and 3,200+ independent sources, with daily refreshes and a feedback loop from the 20,000+ BatchService users on the BatchLeads UI built on the same API.

Coverage extends to 155M+ U.S. properties with 700+ attributes, and the same endpoint surface returns valuations, tax data, sales history, owner records, and verified phone and email contact data. A PropTech build does not have to wire up two vendors to cover the property and the people attached to it.

The public API reference documents every endpoint, and /skip-trace accepts address or APN (Assessor's Parcel Number) input and returns phones flagged mobile, landline, or VoIP, plus emails and verified mailing addresses, up to 100 properties per request with confidence scores. Pay-as-you-go use carries no contracts and no minimums, while subscription tiers and annual commitments are a separate arrangement.

BatchData describes its API as TCPA-safe (Telephone Consumer Protection Act) and CCPA-ready, with DNC (Do Not Call) and known-litigator scrubbing applied before results return. For builds whose customers do outbound work, that posture stands between shipping and a TCPA claim at $500 per violation, trebled to $1,500 when willful.

Pricing is public, and the Growth tier runs $1,000 per month for 100,000 records, scaling through Professional at 300,000 and Scale at 750,000, with Enterprise at 3M on custom terms. Pay-per-match rates run roughly $0.07 to $0.18 per matched record, and data also lands in AWS S3, Snowflake, and Databricks.

BatchData is built for PropTech and fintech teams whose product value depends on owner contact data, including investor prospecting, off-market deal sourcing, and LLC and trust unmasking. The 76% figure is a published top-line, not a guarantee for every dataset, though it remains the highest publicly published contact rate in the category. BatchData is not the right fit if owner contact is incidental to the product, where ATTOM covers the same records without the skip-trace premium, or if the budget cannot clear $1,000 per month, where PropertyRadar's bundled contacts start at $119.

#4 RealEstateAPI (REAPI): Best Developer-First Property API for PropTech Startups

REAPI positions itself explicitly as a big-data-as-a-service platform for PropTech, fintech, and SaaS teams building on top of 159M+ U.S. property records. RealEstateAPI was acquired by Beacon Software in March 2026, and the brand continues to operate under its own name post-acquisition.

REAPI publishes a sub-second response time on tens of thousands of records and a 99.9% uptime claim, with endpoints spanning property search across 100+ parameters, property details, AVM comps, parcel boundaries, and skip tracing. The Smart API framing is the design choice that defines the product, because queries are expressive enough that a builder can replace three or four endpoint calls with one well-constructed request.

REAPI's Starter tier is $599 per month for 30,000 credits, Growth is $1,200 for 150,000, and Pro is $2,500 for 400,000, with a free trial on the way in. Growth and Pro add custom comps, parcel boundaries, map pins, address verification, and bulk endpoints.

Public G2 reviews and independent developer write-ups highlight clear documentation, intuitive endpoint design, and responsive support, plus integrations with HubSpot CRM, Salesforce, Zapier, Bubble, Podio, and GoHighLevel. REAPI is built for PropTech startups shipping distressed-property prospecting tools, parcel-mapping products, or lender lead-gen workflows where expressive search and clean JSON matter more than warehouse breadth. REAPI is not the right fit for a team that needs a perpetual free tier, and it loses to BatchData when skip-tracing volume dominates the workload.

#5 HouseCanary: Best Property Data API for AI-Powered Valuations and Forecasts

HouseCanary covers 136M+ U.S. properties with a REST API built around AI-powered AVMs, rental AVMs, and 36-month price and rental forecasts at ZIP-to-block-level granularity, with monthly model refreshes and POST endpoints that batch 100 properties per request and surface 75+ data points per record. HouseCanary also operates a licensed brokerage under the trade name ComeHome, a brand of the same company.

Pricing is annual and per-call, so Basic at $190 per year carries no API access, Pro at $790 and Teams at $1,990 include the core API, and Property Analytics calls run from $0.50 up to $6 for premium-plus endpoints. HouseCanary is built for PropTech builds whose core value is residential valuation accuracy or forward market forecasting, including single-family rental investor tools, lender underwriting, and digital banking platforms where AVM quality is the product.

#6 CoStar: Best for Enterprise Commercial Real Estate API Use Cases Only

CoStar remains the broader real estate technology category leader for commercial real estate data, with 5.3M sale comps, 15.2M lease comps, and 8.2M tenant profiles on its U.S. platform, but its API is enterprise-scoped and built for large CRE consumers, brokerage platforms, and institutional clients. Third-party data from Vendr places CoStar contracts between $3,000 and $23,000, averaging $15,130, and every one of those deals started with a procurement conversation.

CoStar Group (NASDAQ: CSGP) has expanded by acquisition, taking Matterport in February 2025, Domain Holdings Australia in August 2025, and Zonda for $800M on August 21, 2026. CoStar is the answer when the buyer is an enterprise CRE platform with procurement, legal, and budget for a six-figure data contract, and for a startup on residential property data, the five self-serve options above are the practical starting points.

#7 Cotality (formerly CoreLogic): Best for Enterprise Residential and Mortgage API Use Cases Only

Cotality (formerly CoreLogic, rebranded March 2025) is a long-established enterprise data provider for residential property, mortgage, and risk datasets, with APIs aimed at lenders, insurers, and large PropTech players that need curated data on negotiated terms (independent developer guide). Its persistent CLIP identifier spans 157M+ IDs at a 99.2% customer-portfolio match rate, the join key enterprise buyers are paying for.

Cotality is appropriate for enterprise residential lenders, insurance carriers, and institutional PropTech platforms with the procurement runway to license its datasets, and no U.S. list price is published for those products. It is not the right starting point for startup-stage builds, where PropertyRadar or ATTOM ship the same workflows faster with self-serve onboarding.

How to Choose a Property Data API by Team Stage and Use Case

Team stage and the dominant data primitive decide this purchase for most PropTech builds, and the table below maps them together. A startup-stage team can run PropertyRadar's API trial alongside ATTOM's free trial key in one week and commit to whichever answers the MVP's data question.

Signing an enterprise contract before validating data fit against the real workflow costs a procurement cycle that the five self-serve options above avoid, since each can be tested in a week for a credit-card charge. The license text matters as much as the endpoint list during that test, because PropertyRadar's end-user restriction and BatchData's pay-as-you-go terms each change what a startup is allowed to ship on top of the data.

Which Property Data API Should PropTech Developers Choose?

PropertyRadar fits when the team is startup-stage or solo, needs owner identity, contacts, chain of title, and comps behind one API key, and builds on its own account or through an approved OAuth partnership. Pick ATTOM if the build needs the broadest U.S. property dataset, a free trial key, and a path from MVP to a Snowflake warehouse on one data foundation. BatchData is the answer when verified owner contact data and skip-tracing accuracy are the core of the product's value, including investor prospecting tools and wholesaler CRMs.

Choose REAPI when developer experience and transparent monthly pricing matter more than warehouse breadth, especially for early-stage MVPs that need expressive property search out of the box. HouseCanary earns the pick when AVM accuracy and forward-looking forecasts are the product itself. CoStar and Cotality make sense for enterprise teams with a CRE or institutional residential mandate, and neither offers a self-serve key that a developer can activate without a sales cycle.

CoStar remains the broader real estate technology category leader overall, and that designation is earned on comps volume no competitor publishes. The practical next step for most startup-stage builders is narrower: activate PropertyRadar's 30-day API trial on a Solo plan and pull an ATTOM free trial key the same week, then let the two answer the data question the MVP depends on before the sprint closes.