A tool to copy Wikipedia categories to another language Wikipedia (Community Wishlist/W375)

Description

English Wikipedia has both by far the most articles and the most categories. Most of its nonhidden categories are useful.

For countless major categories that are useful there is no equivalent in the major nonenglish Wikipedias.

It is difficult to synchronize a category that already exists on English Wikipedia to another language Wikipedia – one has to do all the categorization manually by hand and that's very time-intensive and not feasible for categories with many pages; it's not being done. I think the main reason is that it's not worth the effort/time.

For example, on German Wikipedia there are no equivalents to useful categories like Category:Governance or Category:1960s science fiction novels.

It would be very useful if there was a tool to create a category based on the English category – or ideally even multiple categories – where it goes through all the pages in it, goes to the linked German article and adds the respective category.
Alternatively or additionally, one could also have 'virtual categories' where it shows an English Wikipedia category with the category title machine-translated and it containing the articles in the given language (like German) that are linked to the articles it contains. If the nonenglish Wikipedia has some articles that belong into the category but do not exist in English Wikipedia, those would be missing but such are quite rare and every category can be slightly incomplete in any case and it's quite useful nevertheless.

Note that this also applies to Commons where one often has to recreate or populate/complete categories already in English Wikipedia (note: rarely also the other way around). Also note that this category synchronization tool could also be used to highlight which articles are missing in a given language version compared to another one or even create a virtual multi-lingual category with articles of multiple languages for those users who can speak multiple languages.

One could also use this to synchronize changes like addition and removals of categories on categories on English Wikipedia that also exist on Commons – the tool could for example show these changes as suggested changes to users of the tool who could then approve the changes one after another to make the edits. Sometimes, this is because a new category was created on English Wikipedia and set on a category after the Commons category pendant for that category has already been created. Sometimes Commons also has valuable category changes that are still missing in ENWP.

Categories are pretty useful to find and filter or browse articles about any given subject such as novels written in a given period, articles about subjects that are recent, and anything else. They can also be used to see stats like the most viewed articles in a given category (and its subcategories) and lists can be made from them. Additionally, metadata about subjects can be inferred from this like the release year and there's various other advantages and uses that I can't all list here. That just English Wikipedia and Wikimedia Commons have a comprehensive category structure greatly reduces the usefulness and quality of other Wikipedias. Moreover, it takes a lot of mundane volunteer time for duplicating work that has already been done.

Assigned focus area

Unassigned

Type of wish

Feature request