I am currently in the process of developing an open-source computer application and it is taking up a lot of my free time, so I would like to get some sort of income from it, even if it is a small amount, however I would still like the program to remain open-source. So I figured that on my website I could add a donation button, but then I thought that, legally, this may not be allowed because, I've always assumed that, a donation is intended to be used for the development of the program/thing it was donated for, but since I have no use for donations for use only with the program, as I am only using only open source modules, and I just want it to be used as a bit more income, would I be allowed to ask for a donation on my website? I thought it might be ok if I specify what the donation is for, but I wanted to check so I didn't do anything illegal.
Thanks in advance for help.