Understanding the Relationship Between CDS & APDS

August 29, 2022

As two organizations developing data specifications, APDS and the OMF have a lot in common – most importantly, our mutual commitment to developing tools aimed at creating more accessible, useful curbs. This comprehensive guide outlines how we work together and answers frequently asked questions about the major data specifications that we steward: APDS and CDS.


The CDS (Curb Data Specification) and APDS (Alliance for Parking Data Standards) specifications are two data standards used for expressing and collecting information about vehicle parking and curb usage. 

CDS is a management and regulatory tool that focuses on expressing static and dynamic regulations, and measuring activity at the curb. The APDS specification enables entities to share various types of data within the parking and curbside sectors, and with other sectors and users of these resources.

CDS focuses deeply on curb loading zones in the public right of way, while the APDS specification is broader and includes many types of parking facilities and activities across public and private facilities.

CDS is managed by the Open Mobility Foundation, a US non-profit open source membership organization led by cities, governed by public agencies and private companies, with a board composed of public agencies. The APDS specification is an ISO standard and is managed by APDS, a UK limited by guarantee company (not for profit) founded and governed by the British Parking Association, European Parking Association, and The International Parking & Mobility Institute, with a board composed of industry trade groups and private companies.


While there are some similarities and overlaps between the specifications, they have different purposes, scopes, formats, and governance.

Primary Purpose Define all types of parking facilities in a city and provide data interoperability between vendors. Define, monitor, understand, and regulate activity in the public right of way, with an initial focus on commercial loading zones
Secondary Purposes
  • Optimize payment and financial transactions
  • Allow easier smart city solutions 
  • Ability for facilities and operations to share data efficiently
  • Create an ecosystem for curb software and hardware companies
  • Provide public data on curb locations, policies, and usage for the public and companies
  • Assist in overall analysis and management of public right-of-way
Access to Data Private: for cities and curb solution provider vendors

Public: parking facilities and rules 

Private: detailed curb event activity for cities and their vendors

Public: curb definitions, locations, availability, and aggregated metrics 

Scope Wide: Defining many possible aspects of parking Deep: Defining and measuring curb activities
Covered Locations Any type of parking Commercial curb loading zones in the right of way
Geographic Definitions
  • Polygon areas for curbs
  • Latitude and longitude for events
  • Links to linear reference systems
  • Does not replace internal curb inventory, but is connected by reference
Format UML Model and Authenticated JSON APIs, external to spec Relational Data Model and Public and Authenticated JSON APIs, as part of spec
Usage License GNU General Public License Version 3  Creative Commons Attribution 4.0 International Public License
Spec Location APDS Website CDS GitHub Repository
Permit Policy Guidance Not Applicable OMF CDS Policy Language Guidance
Governing Organizations APDS / IPMI / BPA / EPA

Limited by guarantee (not for profit) company based in the UK

Open Mobility Foundation

Nonprofit (501c6) foundation based in the US



Because APDS covers a wider width and breadth of parking and curb management across a city and CDS is deeper and more specific to curbs, APDS recommends using CDS for dynamic curb management and metrics, and OMF recommends using APDS for all other parking related data exchanges.

Shared Goals

APDS and OMF have similar goals, namely to provide operators, municipalities, and any related organization that supports parking, curbside, and mobility services with a common framework to share and communicate data across entities.

Areas of Potential Collaboration 

Cities across the globe are investigating means to communicate the status of parking and curbside activity via consistent methods using common and relevant data specifications.  The relationship between parking and curbside activity is obvious, and connection between the two will become more important as each spec is adopted. 

By collaborating, OMF and APDS will be able to further the adoption of global data specifications that support parking, mobility and curbside needs. Currently, both OMF and APDS have pilots and projects underway to support curbside management practices. The convergence of parking and curbside activities is inevitable; both OMF and APDS benefit by offering a unified approach to data sharing and establishing complementary definitions and tools for entities to use. Ideally, an entity could adopt both CDS and APDS data specifications in concert to achieve greater information sharing and partnership potential.  

Specification Alignment

Many organizations choose to implement both specifications, as they were created independently of each other and serve different primary purposes. To reduce technical burden and increase the utility of both APDS and CDS, the OMF and APDS will work together to increase alignment between the specifications – we keep abreast of each other’s progress and regularly review planned changes to find opportunities for potential alignment.

While there is no plan to fully reconcile the standards, as new features are added there may be more opportunities to use shared data models, enumerations, nomenclature, or other technical structures. Ultimately, each specification will remain independently governed to serve its unique purpose, but the data ecosystem will be stronger as APDS and the Open Mobility Foundation coordinate and communicate about the direction of our respective work.


What is the difference between APDS and CDS?

    • APDS’ data spec is an ISO standard governed by APDS that defines many parts of the parking ecosystem including on-street parking, garages, private vehicles, and commercial curb access. 
    • CDS is a free and open source standard governed by the OMF that helps cities and companies pilot and scale dynamic curb zones that optimize commercial loading activities of people and goods. CDS provides a mechanism for expressing static and dynamic regulations, measuring activity at the curb, and developing policies that create more accessible, useful curbs.

What is the difference between the governing organizations and process for development?

  • Org type/tax status
    • APDS is a privately-owned limited by guarantee (not for profit) UK company.
    • OMF is a city-led US nonprofit (501c6) foundation.
  • Governance/board/funding
    • APDS is led by a diverse board of companies and institutions that builds a data standard around the greater parking ecosystem. Membership is free, and APDS is funded by volunteer donations and contributions from its three parent organizations. – website
    • OMF is a city-led nonprofit that develops free and open source standards and tools through a governance structure that brings together public and private sectors. OMF’s governance is designed to emphasize transparency, consensus, and formal approval by its leadership, which is composed of OMF’s members. The OMF is a non-profit membership organization, funded by annual member dues and philanthropic support. – website

How do the organizations work together?

  • To reduce technical burden and increase the utility of both ADPS and CDS, the OMF and APDS work together to increase alignment between the specifications
    • As CDS is an open standard, APDS plans to attend working group planning calls, participates in the open source community on GitHub, and regularly reviews planned changes to find opportunities for potential alignment.
    • OMF will stay involved with APDS as development work continues and will look to APDS for advice on how to align our work.

Who uses it and why?

  • CDS is used by public agencies managing their curb space, by fleet operators accessing the curb, and by hardware and software companies that monitor activity at the curb.
  • APDS is used by companies and vendors managing parking across an agency and transactions that occur between cities, vendors, and parking users.
  • APDS covers a wide width and breadth of parking and curb management across a city and CDS is deeper and more specific to curbs. CDS is used for dynamic curb management and metrics, and APDS is used for all other parking related data exchanges.

Who is already using it?

  • Each spec is used globally by dozens of cities and companies

What types of data fields does it cover?

  • APDS covers a broad range of data fields around places, rights, rates, sessions, observations, occupancy, and quotes across all manner of parking. It does not have the same level of depth at the curb as CDS does around fleet operator and sensor data and curb metrics.
  • CDS covers details around curb locations, policies, status, availability, events, sessions, and metrics in the public right of way. It does not have the same breadth of data that APDS does around all types of public and private parking.

How is the data formatted and delivered?

  • CDS is a series of static or dynamic APIs and endpoints that are hosted or consumed by agencies, sensor companies, software providers, or curb users. The structure and fields are clearly defined and data is returned as public or private JSON files.
  • APDS defines a hierarchy of objects, fields, and relationships between various areas of the parking lifecycle, but does not define API endpoints or data formats, leaving that up to the data implementers. 

How can I use APDS and CDS together/what use cases would they meet when used together?

  • An agency could use APDS to define all of its parking spaces and allow companies to exchange information across disparate vendor platforms, and also use CDS to manage the subset of curb zone details, activities, and metrics. It would also be possible for CDS and APDS to transfer some of their data back and forth between the two specs.
  • Given that both specifications are relatively new, more full implementations by public agencies and private sector companies are needed to fully flesh out the ways in which they work together, and what major incompatibilities exist. 

What tooling or support is needed to implement each specification?

  • CDS is meant to be a very flexible, lightweight, accommodating, and easy-to-implement solution for curb management that can sit on top of existing systems. A public agency could manage some of this with static files and existing systems, but would likely rely on a vendor to implement all of CDS’s features and capture curb activity.
  • APDS is a larger, more robust ISO standard that defines how data is exchanged, so many vendor systems could use the spec to share data, sometimes without the need for overarching agency support.

How was each spec developed and built, and who is using it?

  • APDS released Version 4.0 of its APDS data specification in June 2022.  The specification was adopted as an ISO technical specification in February 2022. Over a two-year process, this effort included over 600 entities, and 45+ countries that reviewed and adopted the ADPS data specification.
  • OMF released the initial 1.0 version of the Curb Data Specification (CDS) in April 2022, after a year and a half of work by 160+ individuals and 70+ public and private organizations in 36 working group meetings, each with publicly-available recordings, slides, and notes. At launch, CDS was already being used internationally by over two dozen organizations and the OMF continues to support technical implementation and gather real-world feedback to inform development of future versions.


APDS is a not-for-profit organization developing, promoting, and maintaining uniform global specifications for parking and curbside related data that allows entities to share the data worldwide.  The APDS specification enables entities to share various types of data within the parking and curbside sectors and, more importantly, with other sectors and users of parking and curbside resources.  As smart-city, curbside management and mobility efforts continue to expand, the ability for facilities and operations to share data efficiently and cost effectively is important to the continued success of the sector.


The Open Mobility Foundation (OMF) is a non-profit foundation that develops open source tools for cities to manage mobility, starting with the Mobility Data Specification (MDS) in 2019 which is now used by over 150 cities around the world.  By providing governance and leadership, OMF offers a safe, efficient environment for stakeholders including municipalities, companies, technical, privacy, and policy experts, and the public to shape urban mobility management tools that help public agencies accomplish their mobility policy goals.


See the external document.


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