---
title: "Retrieve the list of geospatial data collections available from this service."
method: GET
path: "/collections"
tags: ["Data Collections"]
---

# Retrieve the list of geospatial data collections available from this service.

`GET /collections`

## Response `200`

The collections of (mostly geospatial) data available from this API. The dataset contains one or more collections. This resource provides information about and access to the collections. The response contains the list of collections. Each collection is accessible via one or more OGC API set of specifications, for which a link to relevant accessible resources, e.g. /collections/{collectionId}/(items, coverage, map, tiles...) is provided, with the corresponding relation type, as well as key information about the collection. This information includes:
* a local identifier for the collection that is unique for the dataset;
* a list of coordinate reference systems (CRS) in which data may be returned by the server. The first CRS is the default coordinate reference system (the default is always WGS 84 with axis order longitude/latitude);
* an optional title and description for the collection;
* an optional extent that can be used to provide an indication of the spatial and temporal extent of the collection - typically derived from the data;
* for collections accessible via the Features or Records API, an optional indicator about the type of the items in the collection (the default value, if the indicator is not provided, is 'feature').

- Collections
  - `links` Link[], required
    - `href` string, required — Supplies the URI to a remote resource (or resource fragment).
    - `rel` string, required — The type or semantics of the relation.
    - `type` string — A hint indicating what the media type of the result of dereferencing the link should be.
    - `templated` boolean — This flag set to true if the link is a URL template.
    - `varBase` string — A base path to retrieve semantic information about the variables used in URL template.
    - `hreflang` string — A hint indicating what the language of the result of dereferencing the link should be.
    - `title` string — Used to label the destination of a link such that it can be used as a human-readable identifier.
    - `length` integer
  - `collections` CollectionInfo[], required
    - `id` string, required — identifier of the collection used, for example, in URIs
    - `title` string — human readable title of the collection
    - `description` string — a description of the data in the collection
    - `links` Link[], required
      - `href` string, required — Supplies the URI to a remote resource (or resource fragment).
      - `rel` string, required — The type or semantics of the relation.
      - `type` string — A hint indicating what the media type of the result of dereferencing the link should be.
      - `templated` boolean — This flag set to true if the link is a URL template.
      - `varBase` string — A base path to retrieve semantic information about the variables used in URL template.
      - `hreflang` string — A hint indicating what the language of the result of dereferencing the link should be.
      - `title` string — Used to label the destination of a link such that it can be used as a human-readable identifier.
      - `length` integer
    - `extent` ExtentUad — The extent module only addresses spatial and temporal extents. This module extends extent by specifying how intervals and crs properties can be used to specify additional geometries.
      - `spatial` ExtentSpatial — The spatial extent of the data in the collection.
        - `bbox` array[] — One or more bounding boxes that describe the spatial extent of the dataset. In the Core only a single bounding box is supported. Extensions may support additional areas. The first bounding box describes the overall spatial extent of the data. All subsequent bounding boxes describe more precise bounding boxes, e.g., to identify clusters of data. Clients only interested in the overall spatial extent will only need to access the first item in each array.
          - number[] — Each bounding box is provided as four or six numbers, depending on whether the coordinate reference system includes a vertical axis (height or depth): * Lower left corner, coordinate axis 1 * Lower left corner, coordinate axis 2 * Minimum value, coordinate axis 3 (optional) * Upper right corner, coordinate axis 1 * Upper right corner, coordinate axis 2 * Maximum value, coordinate axis 3 (optional) If the value consists of four numbers, the coordinate reference system is WGS 84 longitude/latitude (http://www.opengis.net/def/crs/OGC/1.3/CRS84) unless a different coordinate reference system is specified in a parameter `bbox-crs`. If the value consists of six numbers, the coordinate reference system is WGS 84 longitude/latitude/ellipsoidal height (http://www.opengis.net/def/crs/OGC/0/CRS84h) unless a different coordinate reference system is specified in a parameter `bbox-crs`. For WGS 84 longitude/latitude the values are in most cases the sequence of minimum longitude, minimum latitude, maximum longitude and maximum latitude. However, in cases where the box spans the antimeridian the first value (west-most box edge) is larger than the third value (east-most box edge). If the vertical axis is included, the third and the sixth number are the bottom and the top of the 3-dimensional bounding box. If a feature has multiple spatial geometry properties, it is the decision of the server whether only a single spatial geometry property is used to determine the extent or all relevant geometries.
        - `crs` 'http://www.opengis.net/def/crs/EPSG/0/3857' | 'http://www.opengis.net/def/crs/EPSG/0/3857h' | 'http://www.opengis.net/def/crs/OGC/1.3/CRS84' | 'http://www.opengis.net/def/crs/OGC/0/CRS84h' — Coordinate reference system of the coordinates in the spatial extent (property `bbox`). The default reference system is WGS 84 longitude/latitude. In the Core the only other supported coordinate reference system is WGS 84 longitude/latitude/ellipsoidal height for coordinates with height. Extensions may support additional coordinate reference systems and add additional enum values.

## Other responses

- `400` — The request was not supported.
- `404` — The requested resource does not exist on the server. For example, a path parameter had an incorrect value.
- `405` — The HTTP method requested is not supported. This endpoint only supports 'GET' requests.
- `406` — A request header value was not supported.
- `500` — A server error occurred.
- `504` — Gateway Timeout.

---

[API](https://skmtc.net/ordnance-survey/apis/ngd-tiles.md) · [All operations](https://skmtc.net/ordnance-survey/apis/ngd-tiles/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/ordnance-survey/ngd-tiles/revisions/7f01b91d9389/schema)