Unity provides standard Spline asset https://docs.unity3d.com/Packages/[email protected]/manual/getting-started-with-splines.html
Bezier curve editor for Unity game engine
Unity Asset store: https://www.assetstore.unity3d.com/en/#!/content/59043
Docs: http://www.bansheegz.com/BGCurve/
Video (click to view on youtube):