Spark API vs Realie Property Data API for AI agents
FBS's Spark API and RESO Web API give authorized applications access to MLS data on the Flexmls/Spark platform. Realie Property Data API is a US property data API (REST, CLI and MCP) for parcel lookup, property search, owners and comparables; its docs describe property records, not MLS listings.
The short answer
- Spark API: Apps built for agents, brokers or MLSs that use Flexmls, where the MLS member authorizes access.
- Realie Property Data API: Cheap, agent-friendly lookups of US parcel and owner records, not finding homes for sale or rent.
Side by side
| Spark API | Realie Property Data API | |
|---|---|---|
| Searches | MLS listings (and, for VOW apps, sold data) from participating MLSs, within the roles each MLS grants. | Properties and parcels by address, parcel ID, location or whole areas such as counties. |
| Returns | MLS listing records in Spark or RESO Web API format. | Property and parcel records with owner details and comparables. |
| Before the first call | A free developer account, then an MLS data plan or an MLS member who authorizes your app. | A Realie account, an API key from the dashboard, and a payment method on file before sending API requests. |
| Free | Developer account sign-up is free. | Free plan: $0 a month with 25 tokens a month. |
| Paid | $50 a month for each MLS you access, once you have data from your first MLS (MLS data plans may set their own terms). | Tier 1: $50 a month for 1,250 tokens. |
| Acting on a result | Not stated on its pages | Nothing: no agent or landlord contact is described (it has owner tools, not listing contacts). |
| Limits on keeping or showing results | No storing MLS content except temporary caching for performance, unless your key permits replication; MLS display rules and license terms apply. | Not stated on its pages |
| Coverage | Participating MLSs on the FBS platform; no list or count on its pages. | US nationwide property data. |
| MCP server | No official server listed | Official MCP server: https://app.realie.ai/api/mcp (OAuth sign-in) |
Where Openpath fits
Openpath has no homes listed yet. Owners and landlords can list a home for rent or sale on Openpath today, free, and agents will find it through the same search as jobs and businesses. Get listed.
Questions people ask
What do I need before I can use Spark API?
A free developer account, then an MLS data plan or an MLS member who authorizes your app.
Is Spark API free?
Developer account sign-up is free.
What do I need before I can use Realie Property Data API?
A Realie account, an API key from the dashboard, and a payment method on file before sending API requests.
Is Realie Property Data API free?
Free plan: $0 a month with 25 tokens a month.
Sources
Every line about another company comes from its own pages. Prices and terms change, so check the source before you rely on one.
Spark API, read on October 15, 2026:
- sparkplatform.com/docs/overview/api: “The Spark API allows authorized MLS members to request data through developer applications”
- sparkplatform.com/docs/overview/api: “When IDX applications are purchased, the MLS member must authorize that application to access their data.”
- sparkplatform.com/docs/overview/faq: “It’s free to sign up for a Spark API developer account.”
- sparkplatform.com/docs/overview/faq: “Once you have access to data from your first MLS, API access costs $50/mo for each MLS you can access.”
- sparkplatform.com/docs/terms_of_use/developer_agreement_and_terms_of_use: “except for temporary caching purposes necessary for performance enhancement”
- sparkplatform.com/docs/terms_of_use/developer_agreement_and_terms_of_use: “Compliance with MLS Rules and License Terms regarding MLS Content”
Realie Property Data API, read on October 15, 2026:
- docs.realie.ai/api-reference/pricing: “$0 / Month ... 25 Tokens / Month”
- docs.realie.ai/api-reference/pricing: “$50 / Month ... 1,250 Tokens / Month”
- docs.realie.ai/api-reference/faq: “Add a payment method from Billing before sending API requests.”
- docs.realie.ai: “accessing nationwide property data programmatically”
- docs.realie.ai/api-reference/property-data: “A flexible way to paginate through large areas (such as entire counties) to collect all relevant data.”
- docs.realie.ai/realie-mcp-server: “https://app.realie.ai/api/mcp”