I'm specifically interested in character animation and I need software with decent rigging capabilities. I know most free character animation software is pretty basic, but are there any that actually have usable rigging tools? I don't need Hollywood level features, just something that lets me create simple character animations with bones or similar systems. Animation software for small projects would be perfect since I'm just practicing.
For free character animation software with rigging, Synfig Studio is probably your best bet. It has a bone system for vector characters and it's completely free. The learning curve is significant but there are tutorials. Another option is to use Blender's Grease Pencil with armatures. It's more 2.5D than pure 2D, but the rigging system is powerful. Both require some time investment to learn properly.
If you're willing to consider low-cost rather than free, Spine is worth looking at. It's specifically designed for 2D game character animation with bone based rigging. There's a free trial and the essential version is reasonably priced. It's not general animation software but if you're focused on character animation, it's excellent. For free options, Synfig is really the only one with proper rigging tools that I know of.
I've been experimenting with OpenToonz for character animation and it has some rigging capabilities through the plastic tool. It's not as straightforward as dedicated rigging software but it works. There's a learning curve but there are tutorials specifically for character rigging in OpenToonz. For animation software for small projects, it might be overkill but if you're serious about learning character animation, it's worth the effort.
Don't forget about Moho Debut (formerly Anime Studio). It's not free but it's often on sale for around $50. It's specifically designed for 2D character animation with bone rigging and it's much more beginner friendly than Synfig or Blender. For someone focused on character animation, it might be worth saving up for. The rigging system is really intuitive compared to free alternatives. Sometimes investing in the right tool saves you so much frustration.