OS APIs and ArcGIS

Under the PSGA agreement, Public Sector organisations have access to premium Ordnance Survey (OS) APIs. This StoryMap provides an overview of the APIs and how they can be accessed through ArcGIS. For those that already access OS data in another way, the benefits of both the OS and Esri UK services are highlighted to allow you to make informed decisions about which is right for your organisation.

The Public Sector Geospatial Agreement (PSGA) is an agreement allowing Public Sector organisations to have access to Ordnance Survey data, free at point of use. It is a replacement for the Public Sector Mapping Agreement (PSMA) and One Scotland Mapping Agreement (OSMA) but goes beyond the original remit to cover more products and to also include things that benefit non-public sector organisations. 

If you're not sure if your organisation is a PSGA member, you can search below:

Application Programming Interfaces (APIs) are a set of rules that lets computer systems or programs talk to each other, exposing data and functionality in a consistent format, typically over the internet.

For the OS APIs, this means we can access the data as a web service with a defined interface, which can be called from web applications, desktop systems, scripts or pretty much anywhere else.

There are many OS APIs available on the  OS Data Hub  for you to explore. There are six premium APIs included in the PSGA and three available as Open Data. Let's explore each API in more detail...

Premium APIs:

•  OS Maps API  
•  OS Vector Tile API  
•  OS Features API  
•  OS Places API 
•  OS NGD API - Features 
•  OS NGD API - Tiles 

Open Data APIs:

•  OS Names API 
•  OS Linked Identifiers API  
•  OS Downloads API 

The OS Maps API provides up-to-date, detailed maps of Great Britain available in four cartographic styles. They are delivered as tiled services (WMTS) in both Web Mercator and British National Grid projections. 

When you should use this API:

• You just need a basemap to sit underneath your own data
• You want to use MasterMap Topography and Zoomstack data.

Where you shouldn't use this API:

• You want to select/analyse individual features
• You want to use the tiles offline, for example in a mobile application like ArcGIS Field Maps,
• You need to use other datasets, for example VectorMap Local or VectorMap Local Colour Raster.

OS Maps API in ArcGIS

The OS Maps API is ready to use in web maps created in Map Viewer and in ArcGIS Pro. Maps from the OS Maps API can also be used as basemaps across ArcGIS.

The OS Vector Tile API provides maps in vector tile format for higher fidelity and greater customisability than raster basemaps from the OS Maps API. It includes MasterMap Topography and Zoomstack data that can be viewed down to 1:400.

When you should use this API:

• You want to use MasterMap Topography and Zoomstack data
• You need a customised basemap style for your JavaScript application.

Where you shouldn't use this API:

• You need to use other datasets, for example VectorMap Local or one of the raster stack basemaps (1:25,000 Scale Colour Raster etc.)

OS Vector Tile API in ArcGIS

The Vector Tile API can be used directly in ArcGIS Pro. Maps published from ArcGIS Pro that include the OS Vector Tile API can be used as basemaps across ArcGIS.

The API can also be used in custom web apps built using the ArcGIS Maps SDK for JavaScript. You can see examples of this on the OS page here:  OS Vector Tile API – Display a basic map 

This OS Features API is a service which offers access to OS data as features. This includes open data and MasterMap Topography data, providing direct access to features such as buildings, roads, green spaces and more. It is delivered as a WFS service.

When you should use this API:

• You want direct access to features such as buildings, roads and green spaces
• You need to snap to OS features while editing data.

Where you shouldn't use this API:

• You just need a basemap for reference/to display data over
• You want to use OS features for analysis such as Geoprocessing
• You want to display features over a large area.

OS Features API in ArcGIS

A Connector for OS Features API is available from the  ArcGIS Marketplace  at no additional cost to PSGA members. Layers created using the Connector can be used in most ArcGIS applications. This is the recommended way to access the OS Features API in ArcGIS.

The OS Places API allows 'geosearch' using AddressBase Premium data. A 'geosearch' allows you to locate an address and have the map zoom to that location. The result can be displayed on the map, but the result is not stored in any way for later use.

When you should use this API:

• You want to find a single address on a map using search.

Where you shouldn't use this API:

• You need to convert addresses to map features (geocoding)
• Your addresses are outside of Great Britain, Isle of Man and the Channel Islands.

OS Places API in ArcGIS

The OS Places API requires a connector to work with the ArcGIS. This connector is available in the  ArcGIS Marketplace  at no additional cost to PSGA members.

Introduced in September 2022, the OS NGD API - Features gives you access to the OS National Geographic Database, which contains authoritative data that describes the geography of Great Britain. The data is provided in GeoJSON format and ready to use in many applications (web and mobile). To find out more check out this  blog  or the  OS overview  .

When you should use this API:

• You want direct access to features such as buildings, roads and green spaces
• You would like to explore the data schemas
• You want data with rich attribution for your maps and web applications.

Where you shouldn't use this API:

• If you want to create a scalable map across different GB zoom levels,
• Where you would like to access the OS NGD Address Theme or Administrative & Statistical Units Theme data.

OS NGD API - Features in ArcGIS

The OS NGD API - Features can be added to web maps in Map Viewer or accessed as a content item in ArcGIS Online and ArcGIS Enterprise (from version 11.2 ).

The OS NGD API - Features works in ArcGIS Pro from version 3.4.

OS NGD API - Tiles offers detailed and customisable basemap based on the latest OGC API - Tiles standards that can be optimised for interactive web maps.

When you should use this API:

• You would like to customise the map style, branding and content
• You need to access the maps in different projections (British National Grid and Web Mercator)
• You want to use it as a basemap across web and mobile applications.

Where you shouldn't use this API:

• You would like to access all the detailed attribution from OS data
• You need a basemap for out-of-the-box ArcGIS web applications.

OS NGD API - Tiles in ArcGIS

OS NGD API - Tiles is not currently supported in ArcGIS. Support will be added at a future version.

The OS Names API allows you to find accurate and reliable locations of interest quickly including place names, postcodes, roads and much more. It can support geocoding, routing and navigation by easily locating a named feature or finding the closest location to a given point.

When you should use this API:

• You want to search for areas (including woodlands and forests), cities and roads
• You need to search for postcodes.

Where you shouldn't use this API:

• If you need to bulk-search for addresses
• If you want to search for specific addresses (e.g. house numbers).

OS Names API in ArcGIS

OS Names API data is open data and is already included in the ArcGIS World Geocoding Service, which is the default for address search and geocoding in ArcGIS. The OS Names API itself does not work in ArcGIS.

To find out more about the technical specification or how to get started, view the OS API overview page  here .

The OS Linked Identifiers API allows you to discover the relationship between OS MasterMap features, properties and streets using the key identifiers (TOID, UPRN, USRN). This removes the need to manage and analyse large datasets. All the supported relationships and links can be found listed  here .

When you should use this API:

• You want to find out what addresses exist on a specific street or identify what street a property address is on using the link between USRN and UPRN
• You need to create interactive web maps that can retrieve attribute or address data when features are selected
• You want to link third-party street data to understand and analyse road-related data including traffic speed and accident count.

Where you shouldn't use this API:

• You want to access feature attributes including geometry linked to the identifier - the API only provides details of the related identifiers.

Please note that some of these relationships need Premium OS data and for others, it is possible to create these relationships yourself through analysis of OS OpenData.

OS Linked Identifiers API in ArcGIS

The OS Linked Identifiers API is not supported in out-of-the-box ArcGIS applications, but can be integrated into custom JavaScript applications. Use OS Features API instead if you need to access attribute information and geometry related to identifiers.

The OS Downloads API allows you to automate the discovery and downloads of OS Open Data products and data packages directly to your machine.

When you should use this API:

• You want to understand which OS OpenData products and data packages are available
• You need to automate the download of the OS data available
• You want to request specific spatial areas, data formats and metadata from the OS Open Data dataset.

Where you shouldn't use this API:

• You want to access previous versions of the OS Open Data datasets
• You need to request changes to existing or create new data packages.

OS Downloads API in ArcGIS

Links to download OS Open Data from the OS Downloads API are available in the  ArcGIS Living Atlas . Data downloaded from the API can be used in ArcGIS Pro or published to ArcGIS Online and ArcGIS Enterprise.

Scripts to automate downloads of OS Open Data and Premium data can be built into workflows in ArcGIS Pro using the  osdatahub Python package .

You may be wondering, if you are already using services from Esri UK's Maps+, should you switch to using OS APIs? The choice is up to you, although to help you decide we've summarised the similarities and differences between the services below:

It is important to remember that the OS APIs are based on a different interface to the Esri UK services, which offers different capabilities, so if you plan to switch it may take time to transition. We would recommend trying it out and assessing the impact to your applications, users and workflows.

The  UK Data Loader  is an ArcGIS Pro Toolbox which utilises the power of the Data Interoperability Extension to quickly and easily convert your Ordnance Survey data in a form where it can be used for mapping, visualisation and analysis.

You may need to keep licensing Data Loader if you want to:

• have an offline set of ready-to-use features,
• have an offline copy of AddressBase, AddressBase Plus or AddressBase Premium,
• create locators based on AddressBase Core or AddressBase Premium data,
• use OS Highways as it is not available in the APIs.

You won't need UK Data Loader if you want:

• to be able to use/analyse features through an online tool,
• a basemap,
• to have an offline copy of AddressBase Core (as it is available in GeoPackage format which can be consumed natively in ArcGIS),
• to have an offline set of VML features (available in GeoPackage format).

Ordnance Survey datasets are also available to purchase pre-processed from Esri UK if you do not have the time and resources to process datasets yourself. This includes topographic products, the full AddressBase Suite (including Locators), and Highways with a fully routable network. Please contact your Customer Success Manager or use the contact details below if you would like more information.

If you need more information or help with decided which services to use then please speak to your Customer Success Manager, or contact us on the details below.