The TOAR database offers a REST service to retrieve its data and metadata.
A REST API is a web service, where you can format the URL with question marks and ampersands and issue commands to a web page. These will then be processed and the result returned to you.
https://toar-data.fz-juelich.de/api/v2/ provides a description of the available ReST services.
There are four core endpoints:
stationmeta (describing the station),
timeseries (describing the time series)
variables (describing the variables), and
data (describing the data).