There is a web app: https://www.wh-observer.de/
Unfortunately, only a few TFA devices send data to this website. For me, out of 5 devices, it is just one. See TF website. Only devices with a certain firmware can do it.

You can receive wind every week by email. For rain and temperature, it only works in the TFA app, with a rather old and cumbersome GUI. There is no API for your own website or app (or I couldn't find one). But it would be very desirable.