Hey guys, I was wondering if it's possible to upload multiple files.

It is very time consuming to upload entire sets individually. Is it possible that there's another way?

Pretty much the only way since jdanbooruup stopped working (which was pretty useful when it worked). I use a combination of snaplinks and danbooruup in ff for uploading. Open up a folder in ff and then use snaplinks to open like 20 tabs at a time and copypasta tags into danbooruup.