This page is for developers integrating GroundTruth Layer. For a general overview, click here.
What is GroundTruth Layer?
GroundTruth Layer is a dedicated, continuously maintained MLS data environment operated on behalf of each customer. It’s designed to be used as a primary data layer in production systems, not as an API feed you ingest and rebuild downstream.
In practice, teams use GroundTruth Layer to power:
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listing search and filtering
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map-driven experiences
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autocomplete
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analytics and reporting
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AI and ML workflows
Platform Model (Not IDX)
GroundTruth Layer is not an IDX solution and does not grant IDX display or redistribution rights.
Customers are responsible for obtaining MLS data access/authorization and meeting MLS compliance obligations for their specific use case. GroundTruth Layer operates as a technical subcontractor and data processor, supporting approved MLS use cases on behalf of authorized customers.
Core Guarantees
Real-Time MLS Data Foundation
GroundTruth Layer provides a managed foundation with:
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Freshness: continuously synced (typically <5 minutes, depending on MLS constraints)
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Normalization: cleaned, consistent field meanings across sources
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Determinism: stable identifiers and predictable behavior you can build against
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Customer isolation: a managed data environment per customer (logical isolation)
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No downstream rebuild: you query the platform directly without running ingestion pipelines
Access Surfaces
All access surfaces operate on the same dedicated MLS data environment. Customers can query and extend their dataset while updates, removals, photos, and corrections are handled continuously behind the scenes.
1) Structured Search & Filters
Use this when you need deterministic, structured querying.
Common capabilities:
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listing search and filtering
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sorting and pagination
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bounded geospatial filtering (bbox, radius, polygon depending on integration)
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customer-defined segments and classifications (see below)
2) Map Surfaces
Use this when you need performant, interactive maps at scale.
Designed for:
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pan/zoom performance
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large inventories
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predictable clustering behavior
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filter-consistent map + list results
3) Location & Navigation (Autocomplete)
Use this for navigation and intent capture.
Designed for:
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typo-tolerant place/address suggestions
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proximity-aware ranking (when user location is available)
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map-driven workflows (search-as-you-move, location-first UX)
4) AI-Ready Access
Use this when you want semantic or LLM-style interactions on top of MLS truth.
Typical workflows:
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natural-language queries grounded in structured MLS data
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semantic similarity (“find homes like this”)
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ML-ready datasets (clean text/images/history for training pipelines)
Customer Extensions: Segments and Classifications
GroundTruth Layer supports customer-defined segments and classifications that behave like native fields within your dedicated data environment.
This is how teams implement:
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business-specific naming (“Residential Single Family Homes, For Sale”)
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reusable saved filters
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derived groupings used across search, maps, analytics, and AI workflows
Conceptually:
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A segment is a saved definition (rules + filters) that resolves to a deterministic set of listings.
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A classification is a derived label (or family of labels) computed from MLS fields and/or customer rules.
These extensions are designed to let customers express product-specific definitions without modifying or rebuilding MLS ingestion pipelines.
Operational Transparency
Trust & Transparency
GroundTruth Layer exposes operational signals so you can monitor behavior and build confidently:
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data freshness / last update timestamps
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sync status and health indicators
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inventory metrics (counts by status, removals, etc.)
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explicit handling of listing removals, status changes, and corrections
The goal is simple: teams should always know what they’re building on.
Recommended Integration Patterns
Pattern A: Search + Detail Fetch
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Use structured search to retrieve listing IDs + essential fields
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Fetch details by listing ID on demand
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Keep map rendering lightweight (tiles/cluster surfaces), and load details when users click
Why teams like this:
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fast UI
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predictable performance
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clean separation of concerns
Pattern B: Map-first UX
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Use map surfaces for interactive browsing
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Use structured search for list view and refinement
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Ensure map/list share the same filter model and segments
Why teams like this:
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consistent results across views
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avoids heavy bbox queries on every drag
Pattern C: AI Assist on top of Truth
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Use structured filters to enforce hard constraints (price, beds, geo, status)
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Use AI-ready access to rank, summarize, or explain results
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Keep structured MLS truth as the gatekeeper for compliance-sensitive behavior
Why teams like this:
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avoids “LLM hallucination” as the source of truth
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creates explainable AI experiences
MLS Data Handling & Customer Relationship (Developer Summary)
GroundTruth Layer is operated as a technical subcontractor and data processor. MLS data is processed at the customer’s direction, using the customer’s authorized MLS access, and solely for the customer’s permitted use cases.
GroundTruth Layer does not claim independent rights to MLS data, does not license MLS data, and does not act as an MLS participant, broker, agent, or data distributor. MLS data remains governed by the customer’s direct relationship and agreements with the MLS.
Compliance Support (Developer Summary)
The platform is designed to faithfully implement documented MLS data-handling requirements that are known and technically enforceable at the data layer, including:
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update frequency and freshness handling
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removals and status change processing
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retention limits (where applicable)
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attribution fields (where applicable)
MLS compliance also includes requirements tied to customer applications, including:
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display rules and disclaimers
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branding/logo placement
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advertising usage restrictions
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end-user access controls
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downstream redistribution
Those requirements are implemented by customers and remain outside the platform’s direct control. Customers remain responsible to the MLS for compliance obligations arising from their use of MLS data.
Next Steps
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See the general overview: (link)
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Request access / integration support: (link)
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View API reference: (link)
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View compliance details: (link)