Dear Huebi

I think you are looking for a tn_url.

I suggest you use pwg.categories.getList maybe with an argument: recursive=true

(see https://piwigo.org/demo/tools/ws.htm)

for example:

curl -X POST 'https://piwigo.org/demo/ws.php?format=json&method=pwg.categories.getList&recursive=true'

and look for the values of tn_url corresponding to category/album with id and name.
you can even add id=AlbumID to the query above, if you are interested in a specific album.



Best wishes

panda