Piskel is a free and open source online sprite editor. I use it to quickly edit my sprites. Online version was bit slow and browser froze a lot. Offline version is fine. Because I was using Linux Mint 17, I was getting an error libudev.so.0 not found. I was able to solve it by running the command sed -i ' s/udev\.so\.0/udev.so.1/g ' nw