This tool will provide category tree dumps. Category tree dumps are provided as lists of plain category-to-category links (json file). So, this is kind of "categorylinks" table snapshot, that can be downloaded from https://dumps.wikimedia.org. But there are differences: 1) this is not a sql dump, this is json with data ready to use by software; 2) page-to-category links are not included. So, our dumps are not so huge as raw dumps; 3) extraction of new data may be requested once per day or more (but there will be some limit to prevent service blow). The service is meant to use by new generation bots that use recursive category tree analysis. Previously, such bots used services like "catscan2", "catscan3", "petscan". But everyone knows that these tools are unstable or down from time to time. And there is no cure to fix this. With the new service all heavy recursive processing is carried out on bot side.