it's an application that runs on a mac, on a desktop, not on an iphone or ipad. it allows you switch between *booru sites and query them using tags, and presents a contact sheet with the results, this resuts are obtained and parsed from posts/index.xml, if you like the images you could select them and the application downloads the images, mind you, it can only do that from the contact sheet so it can only download 16 images that come on 1 page of results at the most at one particular time.
The problem is this: i issue an urlrequest to danbooru.donmai.us and i get a urlresponse of 200 and xml with 20 results, i do the same to behoimi.org and i get a 403 response and the xml i get is one just explaining the error, so my questions are, do you allow API requests at all? Do you require cookies to connect to the API urls?