Hey there @basdebruin
I’ve just had a look within our API docs and I wasn’t able to figure out a way to tell if a board is a template or not via the API, but I’ll double-check this with the team to be sure.
That said, you can always see if a board is a template or not within the template store, and each template has its own template ID that you can see as well. Would it make any sense to paste the template ID into the board description for now? You could then query boards by this object:
I definitely agree it would make sense to add this as a field you could query from within the API directly. I’ve passed that as a suggestion to the team