Hello everyone,
In 2015 Wikimedia Germany published the Service Catgraph[1], a graph database of the categories of Wikipedias, as well as Deepcat[2] a gadget for Wikipedia users to search for articles in a category, including recursive subcategories, in the search page of Mediawiki. Since 2018 this functionality is built in the search engine of Wikipedia as well as into the Advanced Search GUI.
Wikimedia will therefore sunset Catgraph as well as Deepcat. We plan to shut down the service end of January. Catgraph also powered other tools such as Catcycle[3] and Article List Generator[4], these will also stop working. If your wiki has deepcat enabled as a gadget or in your globar.js, or you have it in your common.js you should remove it and use the newer, built in 'deepcategory'.
Documentation for the new search-keyword can be found here: https://www.mediawiki.org/wiki/Help:CirrusSearch/de?uselang=de#Deepcategory Documentation for the new Graph-Database is available here: https://www.mediawiki.org/wiki/Wikidata_Query_Service/Categories
Cheers, Michael for the project Technical Wishes at Wikimedia Germany
[1]: https://wikitech.wikimedia.org/wiki/Nova_Resource:Catgraph [2]: https://de.wikipedia.org/wiki/Hilfe:Suche/Deepcat [3]: http://tools.wmflabs.org/render-tests/catcycle-dev/catcycle.py [4]: https://tools.wmflabs.org/render/stools/alg?uilang=en