Real-time parking occupancy data — how many spaces are available right now, by facility and zone — is among the most valuable data parking facilities generate. Drivers benefit from knowing availability before arrival; navigation platforms integrate availability to improve trip routing; municipalities use it for demand management; and operators benefit from demand transparency that supports pricing decisions. Occupancy APIs are the technical mechanism through which this data flows from parking facilities to the platforms that surface it to drivers. Understanding how occupancy APIs work, what data quality requirements apply, and how to integrate with major platforms helps operators participate effectively in the connected mobility ecosystem.

What an Occupancy API Provides

A parking occupancy API is an interface through which external systems can query a parking facility’s current space availability. The minimum useful occupancy API response includes:

  • Available spaces: The current count of unoccupied spaces
  • Total capacity: The facility’s total space count
  • Last updated timestamp: When the occupancy count was last updated (critical for data freshness validation)
  • Facility identifier: A unique ID for the facility (typically a UUID or a well-known ID in the consuming platform’s namespace)

More comprehensive occupancy APIs add:

  • Zone-level breakdown: Available spaces by level, zone, or reserved category (ADA, EV charging, reserved, general)
  • Historical trend data: Typical occupancy by hour of day for consumer-facing availability prediction
  • Rate information: Current pricing to accompany availability in consumer-facing displays
  • Operating hours: Whether the facility is currently open and scheduled to remain open

Data Quality Requirements

An occupancy API that provides inaccurate data is worse than no API — it misdirects drivers, erodes platform partner trust, and can damage the facility’s reputation in navigation apps where users can provide feedback. Data quality requirements:

Freshness: Occupancy data should reflect current conditions, not conditions from 30 minutes ago. For facilities with high turnover (urban transient parking), stale data by more than 5 to 10 minutes can mislead drivers. The last-updated timestamp enables consuming platforms to display data age and suppress stale data.

Accuracy of underlying count: The occupancy API is only as accurate as the underlying data source — PARCS entry/exit counts, per-space sensor data, or manual counts. PARCS count drift (accumulated errors over time from anti-passback exceptions, tailgating, and equipment glitches) degrades API data quality. Regular count audits (manual vehicle counts compared against PARCS counts) are a data quality maintenance requirement.

Failure state handling: When the underlying occupancy data source is unavailable (sensor network outage, PARCS connectivity failure), the API should return a clear status indicating data is unavailable rather than returning stale or incorrect data. Platform partners should treat unavailable status as “status unknown” rather than assuming full availability.

Zero-availability accuracy: When a facility is full, the API should accurately reflect zero availability. A navigation platform that continues to route drivers to a facility showing “3 spaces available” when it is actually full creates a poor driver experience that reflects on both the facility and the platform.

Google Maps Parking Availability Integration

Google Maps displays parking availability information for facilities that provide real-time data. Google accepts parking availability data through its Places API data provider program:

Data format: Google accepts parking data in GTFS-based formats or through direct API partnerships. The specific integration path depends on the scale of the data provider and the integration arrangement with Google.

Facility verification: Google requires facility verification before displaying real-time availability data. The verification process confirms that the data provider has legitimate access to the facility’s occupancy data.

Freshness requirements: Google’s platform has data freshness requirements — facilities that provide data that is regularly stale or inaccurate may be removed from the real-time data display.

Operator benefit: Facilities that appear in Google Maps with real-time availability have higher discovery likelihood from drivers who check parking availability before or during navigation. The distribution value is meaningful in high-demand urban markets.

HERE Technologies and TomTom Integration

HERE Technologies and TomTom are major mapping data providers whose data is used in many navigation systems, automotive navigation, and enterprise mobility applications. Both companies have parking data programs:

HERE Parking: HERE Technologies operates a parking content program that aggregates facility information including real-time availability from facilities that provide data feeds. HERE’s data reaches navigation systems embedded in major automotive brands.

TomTom Parking: TomTom similarly aggregates parking data for automotive navigation systems. Integration with TomTom expands the facility’s reach to automotive navigation users rather than solely smartphone app users.

Both programs have specific data format requirements and partnership arrangements distinct from consumer-facing smartphone navigation apps.

Webhook-Based Availability Notifications

Pull-based APIs (where the consuming system periodically asks “what is the current availability?”) are the most common occupancy data integration pattern. Push-based webhook notifications are an alternative that reduces latency and API call overhead:

How webhooks work: The occupancy data source sends a notification to a consuming system’s endpoint URL when occupancy changes significantly (drops below a threshold, increases above a threshold, or transitions to full/available status). Rather than the consumer polling every 30 seconds, the producer pushes an update only when the data changes.

Use cases for push notifications: Parking guidance sign networks that display “FULL” when a lot fills and “OPEN” when spaces become available benefit from push-based notification — they don’t need to poll continuously, just to receive the status-change notification.

Webhook security: Webhook endpoints receive data from external sources; they must be secured to prevent spoofed requests. Standard approaches include HMAC signature verification (the producer signs each payload with a shared secret, and the consumer verifies the signature before acting on the payload) or bearer token authentication.

Building an Occupancy API: Implementation Options

PARCS vendor-provided API: Many PARCS vendors include occupancy API capability in their platforms. The entry/exit count maintained by the PARCS is exposed via API. This is the simplest implementation path — no additional infrastructure required. Confirm the API’s update frequency, data format, and authentication mechanism.

Parking guidance system API: Facilities with per-space sensor networks connected to a parking guidance platform can expose the PGS platform’s occupancy data via API. PGS data provides zone-level and space-level granularity beyond PARCS entry/exit counts.

Custom API layer: For facilities with PARCS that lack native API capability or that need to aggregate occupancy data from multiple sources (PARCS count + PGS sensor data), a custom API layer can be built that pulls from underlying data sources and exposes a standardized endpoint to consuming platforms.

Frequently Asked Questions

How often should an occupancy API update? Update frequency should match the facility’s turnover rate. High-turnover urban transient facilities benefit from updates every 1 to 5 minutes. Lower-turnover commuter lots may be adequately served by 5 to 15 minute updates. At minimum, the occupancy API should update whenever the count changes by 5 percent or more.

What authentication is appropriate for a public-facing occupancy API? Public-facing read-only occupancy APIs (providing only aggregate availability counts without facility-specific business data) can be published with API key authentication. API keys are issued to registered partners and allow the provider to monitor usage, rate-limit abusive clients, and revoke access if needed. Sensitive data (transaction details, account information) should never be exposed through public-facing APIs.

How do occupancy API integrations affect PARCS vendor selection? PARCS platforms with well-documented, supported occupancy APIs that update in near-real-time are prerequisites for smart city and navigation platform integration. Operators planning to participate in city smart parking programs or navigation platform partnerships should confirm occupancy API capability during PARCS selection.

What is the difference between static facility data and real-time occupancy data for navigation platforms? Static facility data (location, address, hours, capacity, rates) is updated infrequently and describes the facility’s general characteristics. Real-time occupancy data reflects current availability and changes continuously. Navigation platforms typically maintain static facility data in their own databases and supplement it with real-time availability feeds from operators. Both types of data need to be accurate and up to date.

Takeaway

Parking occupancy APIs are the technical infrastructure through which facilities participate in the connected mobility ecosystem — making real-time availability visible in navigation apps, municipal guidance systems, and smart city platforms that reduce circling traffic. The value is clear; the implementation requirements are defined; and the data quality obligations are non-trivial. Facilities that publish accurate, fresh occupancy data through well-designed APIs gain distribution reach that extends far beyond their signage and website. Those that publish inaccurate or stale data damage their reputation on platforms where drivers can leave feedback — making data quality investment as important as the integration itself.