Is there one?
Like gyazo, lightshot, and others.
I found a little script (.sh) that works for both MAC and Linux. Works like a charm on ubuntu, I made a launcher and put it into the bar menu. All I have to do is press Super + 3 and select the area, then link gets copied to the clipboard after uploading.
The only one I found that has capture and uploads to imgur is MyImgur, but gives an error after uploading, and you have to keep the program running to make it work.