OS Maps API
The OS Data Hub offers various APIs to serve data. The OS Maps API uses WMTS and is ideal for background mapping in WebMap.
Because the extents on this WMTS are stretched beyond the normal OSGB British National Grid CRS (27700), you should choose a different projection for this base mapping layer.
You will require an API key 
and the URL to the OS Data Hub to load a WMTS.
Adding the data
In WebMap manager click Configuration > Layers > Add Overlay on the map.
Select OS Maps API from the drop-down menu and enter a descriptive name.
Click Save and enter your unique API key. Select a layer from the drop-down menu and click. The layer information is derived from the Capabilities document.
Note: 27700 = British National Grid and 3857= Long/Lat WGS84 (Pseudo-Mercator)
| Field | Description |
| Name | An appropriate name that is descriptive of the layer. |
| Opacity | Increase or decrease the opacity |
| Cross Origin | Enable to allow Cross Origin Resource requests (CORS service), for example if the SWD is referencing an external database or using web services to access data. |
| Base Map | Enable to treat this layer as a Base Map. (All added layers are automatically assumed to be data layers). |
| Use Authentication | Enable to force map user to use authentication. This can be in the form of an API key or username/password credentials. |
| URL | URL to the service array. |
| Copyright Statement | Use to customise any copyright information to display on layer.  Related Topics |
| Visible | Enable to make the layer visible in map features. |
| Display Projection | Choose from a supplied list of SRID numbers to determine the data’s projection. More SRID numbers can be added from the CRS options. |
| Request Encoding | Refers to the way data is structured and sent in an HTTP request. Two common methods for encoding request data are REST (Representational State Transfer) and KVP (Key-Value Pair). |
| Layer | Layer name as seen in the Capabilities document. |
| Style | Style name as seen in the Capabilities document. |
| Version | WMTS version used currrently. |
| Preload | Load low-resolution tiles up to pre-load level. |
| Use interim tiles on error | Enable this option to allows WebMap to use an interim (lower resolution) tile if the current tile has an error (e.g. it does not exist). This provides a better visual experience when tiles are not present on the server. |
| Tile Width | Data requests from GeognoSIS are returned in tiles. Use this option to control the tile width (measured in number of pixels). It is set to 256 as default. |
|
Tile Height |
Datasets from GeognoSIS are returned in tiles. Use this option to control the tile height (measured in number of pixels). It is set to 256 as default. |
| Origin X | X Coordinates of origin. |
| Origin Y | Y coordinates of origin. |