By clicking on the "Hasse" button below, you will open a window in which you can make computations in Schubert calculus. By clicking on the "Picture" button, you will easily create some tex files of quivers.

You can use this software online, but for more efficiency and to have more functions, such as producing files, it is better to download it : click here to get the program, put it in a directory, and then run :
tar -xvf class.tar
and then :
java QuiverCalculus

The source code is here.