Toonz, the software used to create Studio Ghibli films like Spirited Away and TV shows like Steven Universe and Futurama, is now OpenToonz. It's open source and free for any budding animator to download and use. Image via Studio Ghibli and Walt Disney Studios.
OpenToonz is powerful 2D animation production software that anyone can now use to make commercial or non-commercial animations. And because its open source, you can modify the source code and develop your own tools as you see fit. You can also download the Effects plug-in from Dwango and the Studio Ghibli developed GTS scanning tool for free as well. Keep in mind, however, that using professional tools won't make you an animator overnight. Still, if you're an experienced animator, or just interested in learning, OpenToonz is a pretty sweet deal. You can download OpenToonz for Windows or OS X at the link below.