Mantra

A professional web animation tool for everyone. Opensource

Screenshots

Hunter's comment

A web-based keyframe animation software. Simple, cool, and sophisticated software for making 2D animations.
This is free and opensource. Timeline editing with keyframes and tween editor with a lot of powerful features are excellent in the workflow.
Web animations are created easily with professional quality without installing any software in your device, you can create awesome animations with this web-based software.

Link

https://jeremyckahn.github.io/mantra/