Welcome to the documentation page about the KNMI Web Mapping Service (WMS) API. This page is meant to get you started with WMS. The API complies with the Open Geospatial Consortium - WMS standard, facilitating integration with WMS clients and geospatial tools and systems.

More information on:

What is WMS?

Using the geographical webservice Web Mapping Service (WMS) you can request map images. The visualized response to a request is a map image (returned as JPEG, PNG, etc.) and is usually displayed in a browser client application.

Most of the parameters of the map visualisation are controlled by the server, and can’t be changed by a client. If more control over the visualisation is needed, it is also possible to run a WMS server (such as ADAGUC) using the underlying dataset as input. It is also possible to request the numerical data used for a WMS request using a WCS request.

Which datasets are available via WMS?

The datasets available via WMS can be found by searching for the tag “WMS” in the Dataset Catalog.

For some datasets, the temporal coverage available via WMS is limited. This means that only a limited history of a dataset can be accessed via WMS. If you would like to display a longer temporal history, consider hosting your own WMS server.

How to use WMS?

To use WMS, many different clients exist. To list just a few:

How to add a WMS service to OpenGeoWeb

  1. Go to the Access tab of a dataset supporting WMS (for example radar-reflectivity-composites)
  2. Copy the URL listed under “Anonymous access via WMS”
  3. Open OpenGeoWeb
  4. Close the Workspace menu
  5. Press the Add sign next to Layer in the Layer Manager
  6. Enter the copied WMS URL into the top search bar of the Layer Select window
  7. Press save in the popup window
  8. Select the dataset using the filter tags
  9. Add the layer to the layer manager

When should I be using an API key with WMS?

For each dataset supporting WMS, there are two WMS URLs available. One for anonymous access, and one with authorization. The anonymous URL can be used directly in any WMS client, but has a shared usage quota and is rate-limited per IP.

If you require more frequent, and reliable access, you should consider using the URL requiring an API key. You need to supply the API key as the HTTP Authorization header. Most web clients do not support adding such a key to the requests. If you still would like to use a web client for your user, consider proxying these requests in your own backend server infrastructure.

Rate limits and quotas for the WMS endpoints
Access Rate Limit Quota
With API key 20 requests per second 1000 requests per hour
Anonymous 1 request per second (per IP) 1000 requests per hour (shared)

Requesting an API key

You can request an API key for WMS in the API Catalog. To request an API key, you will need to register for an account. You can do this by clicking the “Register” button in the top right corner of the page. Once registered, you can request an API key by clicking on the appropriate “Request API Key” button on the API Catalog page. You will receive an email with your API key.