Alternatives To The UDC (Universal Decimal Classification) Knowledge Taxonomy

I’ve been looking for a general taxonomy with breadth and depth, somewhat similar to the Dewey-Decimal, or UDC taxonomies.

I can’t find an expression of the Dewey-Decimal (and tbh it’s probably fairly out of date now) and while the UDC offer a widely available 2,500-concept summary version, it doesn’t go down into enough detail for practical use. The master-reference file is ~70k in size, but costs >€350 a year to license.

Are there any openly available, broad and deep taxonomical datasets that I can easily download that are both reasonably well-accepted as standards, and which do a good job of defining a range of topics, themes or concepts I can use to help classify documents and other written resources.

One minute I might be looking at a document that provides technical specifications for a data-processing system, the next, a summary of some banking regulations around risk-management, or a write-up of the state of the art in AI technology. I’d like to be able to tag each of these different documents within a standard scheme of classifications.