Cartrdge is a portfolio community for creatives working in video games and is great for creating a page and uploading animations in multiple formats such as Vimeo, Youtube, Gif.. etc
Cartrdge
Krita
Krita is a free app for digital painting but also supports 2D animation. It is made by artists that want to see affordable art tools for everyone.
Live2D
Live2D has a bunch of software that allows 2D artists to create animations from their artwork. Available in both FREE and PRO versions.
Endless Reference
Endless Reference is a Youtube channel that focuses on animation reference. Lots of great human locomotion videos from different angles
Bodies in Motion
Bodies in Motion is an ongoing photographic project that aims to document the power, beauty and possibility of the human body in motion. It is freely accessible to all visitors at preview resolution or you can subscribe for higher quality images.
MakeHuman (FREE)
MakeHuman is a free open-source software that allows you to create and pose 3D human characters. Useful for pose reference.
Thinking Animation
Thinking Animation has a great section on the pros and cons of different rigs. As well as a bunch of other resources and tips across the site.
Smearframe – Chat Group
The Smearframe Slack channel is an animation chat group where you can talk about anything from inspiration, tips, rigs and more. Get an invite from the link above and join the fun!
Animator's Resource Kit 