I'd like to train a system that takes text and predicts IAB classes.
Are there any public datasets available for this?
I think this is what you are looking for
if you want to validate your model you can use this free api to validate results of your model
you just need to provide attribution to https://front-page.com
I was looking for that as well and did not find any so far. But this paper describes approach to use Wikipedia data for this.