You cannot edit or create animations on Sketchfab, but you can edit some animation properties.
The animation tools are available in 3D Settings.
From your model, click Edit 3D Settings or add "/edit" to the end of any model URL.
Select the Animation panel in the top left.
Only the model's author can access 3D Settings. Edits you make will not change your original file, they will only affect viewing on Sketchfab.
Cycle Mode & Playback Speed
Here you can set the default cycle mode and playback speed.
Cycle Mode
Cycle One: Loop the default animation
Cycle All: Loop through each animation
No Cycle: Play each animation once, then stop
Playback Speed
x0.1: Play at one tenth speed
x0.5: Play at half speed
x1.0: Play at normal speed
x2.0: Play at double speed
Default Animation
Choose the default animation by clicking it in the list. The "Play" icon indicates the current selection. You can also choose the Static pose as the default.
The Static pose is the default state for solid animation, or the bind pose for skinning animation. The bind pose is the state of the bones when the artist attaches the mesh to it. So in bind pose, the mesh is not deformed at all, it's exactly the same as the original (non-rigged) mesh.
Rename & Delete
Rename or delete an animation from the drop-down menu.
Seamless Loop
Choose Seamless loop if the first and last keyframes should be interpolated.
Re-order
Re-order animations in the list by dragging and dropping.
Saving
Once you've made your adjustments, including position and orientation, be sure to update your model's thumbnail image and default position with Save View and/or save your changes with Save Settings. You can return to your model by clicking either the model's name or Exit.
Also see: